Explanation:

A. Only business accounts can be created as partner users. Partner users must be associated with a business account that has been enabled as a partner account. Person Accounts are designed for business-to-consumer (B2C) scenarios and cannot be enabled as partner accounts. Since UMS has both business and person accounts, it is a key consideration that only the business accounts (DR and CK) can be used for partner users.
B. Assign Partner Community license to partner users. This is the correct license type for partners. The Partner Community license provides access to sales-related objects such as opportunities, leads, and campaigns, which are necessary for partners to collaborate on sales with the parent company. The question states that the DR and CK users do not require access to these objects, but the Partner Community license is still the correct license type to enable an account as a "partner" account, which then allows the creation of "partner" users. Access to these objects can then be further controlled through profiles and permission sets, ensuring the principle of least privilege.

Why other options are incorrect

C. Assign Customer Community Plus license to partner users. The Customer Community Plus license is for customers who require more advanced sharing and reporting capabilities than the basic Customer Community license, but it is not intended for the partner sales channel. Its purpose is different from the Partner Community license.
D. Only person accounts can be created as partner users. As explained above, person accounts cannot be used as partner accounts. This option is incorrect.

Explanation:

The key requirements are:

A public marketing site.
High expected traffic volume.
Optimal performance, especially for repeat visitors.

A Content Delivery Network (CDN) is the foundational technology designed specifically to meet these requirements for public-facing websites.

Here’s a detailed breakdown:
D. Enable and configure the Content Delivery Network so that public content is cached. A CDN works by storing (caching) static content (like images, CSS, JavaScript, and even entire pages) on a global network of servers. When a user visits the site, the content is delivered from the server geographically closest to them. This drastically reduces latency and server load. For repeat visitors, the browser can cache these assets locally, making subsequent page loads extremely fast. Enabling the CDN in the Experience Cloud site settings is a critical step for achieving high performance and scalability for a public site.

Why the other options are incorrect:
A. Schedule Apex jobs to push content to users' browser caches.
This is not a standard or feasible practice. Apex runs on the server and cannot directly push content to a user's browser cache. Browser caching is controlled by HTTP headers set by the server (which a CDN helps with), not by scheduled backend jobs.
B. Use Next Best Action to predict what content to serve to the user's browser.
Next Best Action is a decision engine for presenting personalized recommendations (e.g., "offer a discount," "suggest this product"). It is a logic and personalization tool, not a performance and caching tool. It does not inherently make the site load faster; in fact, dynamically generating personalized content can sometimes add minimal overhead compared to serving cached static content.
C. Disable Visualforce to make all pages switch to Lightning.
While it's a best practice to use modern Lightning components, simply disabling Visualforce pages will not force a site to perform better. The site's template and runtime (e.g., LWR) have a much greater impact on performance. Furthermore, this action doesn't address the core requirement of efficiently delivering content to a global audience, which is the specialty of a CDN.

Reference
Salesforce Help: "Improve Site Performance with a Content Delivery Network" - This document explains that "A content delivery network (CDN) can improve your site’s performance and scalability... A CDN is a system of distributed servers that deliver web content to a user based on the user’s geographic location."

Key Concept: For any public-facing Experience Cloud site with expectations for high traffic and global reach, enabling and configuring the Content Delivery Network (CDN) is the single most important performance and scalability action an administrator can take.

Explanation:

The requirement is to configure the search bar's autocomplete suggestions specifically for guest users. This configuration is performed directly on the Search component within Experience Builder.

Here’s a detailed breakdown:

C. In the Search component property editor, open the Autocomplete section and click desired objects to appear in autocomplete. Select "publicly available". This is the precise, declarative path to configure this feature. Within the Autocomplete settings of the Search component, you select which objects should provide suggestions. Crucially, you must then set the visibility of these suggestions to "publicly available" to ensure they are visible to guest (unauthenticated) users. If this is set to "members only," guest users will not see the suggestions.

Why the other options are incorrect:

A. Use the Developer Console to add code to allow for autocomplete functionality. This is unnecessary. Autocomplete is a standard, out-of-the-box feature of the Search component. No custom code is required to enable it.

B. In Salesforce Setup, type "support settings” in the quickfind box. Under the Autocomplete header, select the objects to appear in autocomplete for guest users. The "Support Settings" in Setup generally apply to the standard Salesforce Service Cloud console and may affect internal features, but they do not control the configuration of the Search component within a custom Experience Cloud site. The configuration is done in Experience Builder.

D. In the Hero component property editor, open the Search Results section and click desired objects to appear in autocomplete. Select "publicly available". This is incorrect for two reasons. First, the Hero component is a specific type of banner component and does not contain Search Results settings. Second, even if it were the correct component, the Search Results section controls what appears after a search is executed, not the Autocomplete suggestions that appear while typing.

Reference
Salesforce Help: "Configure the Search Box Component" - This documentation details the Autocomplete settings, explaining how to select objects and set their availability to "publicly available" for guest users or "members only" for logged-in users.

Key Concept:
Configuration for an Experience Cloud site's look, feel, and component behavior is primarily done in Experience Builder, not in the main Salesforce Setup menu (unless it's a global site setting). The Search component's properties are the correct place to manage its autocomplete behavior.

Explanation:

B. Customer Community Plus
The Customer Community Plus license typically supports 20 custom objects per user. This is double the limit of the standard Customer Community license, making it a viable option for UC's requirement of "more than 10" custom objects. This license is generally for customers who need more advanced features, including the ability to use the full Salesforce sharing model (Roles and Sharing Rules).

D. External Apps
The External Apps license (often seen as a high-power, highly custom external user license) is designed for building comprehensive digital experiences that might be fully custom or serve as a dedicated portal for a large number of custom objects. The External Apps license can support up to 200 custom objects per user, far exceeding the 10-object limit and making it a strong fit for a complex, custom solution like the one described.

Incorrect Answers

A. Channel Account
This license is specifically for Partner (resellers, distributors, etc.) users, not Customer users, as required by the prompt. While a Partner license supports more custom objects than a standard Customer Community license (typically 10), it is intended for a different relationship type (B2B/channel management).

C. Commerce Portal
The term "Commerce Portal" is often a feature or a templated site type rather than a distinct core license SKU that meets the custom object count requirement. The license used to power a Commerce Portal is usually a variation of the Customer or Partner licenses, and the specific requirement is the ability to support the large number of custom objects. For high custom object needs, the Customer Community Plus or External Apps licenses are the dedicated choices for external users.

Explanation:

This question addresses the architectural decision of where to build an internal employee application. The key is understanding the benefits of building it within the existing, single org.

Why C is Correct:
Building the HR help desk app in the main org is a best practice. This allows the application to natively leverage the existing organizational data and structure, including:

The Role Hierarchy:
For routing cases and approvals based on an employee's manager or department.
Sharing Rules & Teams:
To control access to sensitive HR cases.
Existing Employee Data:
User records, profiles, and permission sets are already managed in the main org.
Unified Reporting:
HR can report on service metrics alongside other business data.

Creating a separate org would fracture this data and require complex, error-prone integration.

Why the Other Options are Incorrect:
Why A is Incorrect:
There is no product called "Employee Cloud." Employee applications are built using Experience Cloud with specific internal user licenses. The "HR User" profile is not a pre-defined, restricted profile; it would be a custom profile based on the needs of the HR help desk.
Why B is Incorrect:
While employee privacy is critical, creating a separate org is an extreme and operationally complex solution that is generally not recommended. Data privacy and security can be effectively managed within a single org using robust Salesforce security tools like profiles, permission sets, sharing settings, and record data classification. A separate org creates significant integration overhead and data silos.
Why D is Incorrect:
This is factually incorrect. Experience Cloud (which is used to build internal employee apps) is not limited to Enterprise and Performance editions. It is available on a range of editions, including Professional (with an add-on), Enterprise, Unlimited, and Performance. Furthermore, there is no specific "HR permission set license" required; standard internal user licenses (like the "Employee" license) are used.

Reference:
Salesforce Help: Build an Employee Help Desk - This guide outlines the process of building an internal help desk within a single Salesforce org.