Explanation:

In Salesforce Industries CPQ, the linkage between a Document Template and objects like Opportunity, Quote, or Order is controlled via the Applicable Objects setting within the Template Settings section of the Document Template record.

✅ B. Applicable Objects in Template Settings
This field defines which Salesforce standard or custom objects the template can be used with.
Common values include:

Opportunity
Quote
Order

When generating a document, the system checks this field to determine whether the template is valid for the current object context.

❌ Why the other options are incorrect:

A. PDF Document Template custom setting
This is not a standard mechanism for linking templates to objects.
Custom settings may control behavior or defaults, but not object applicability.

C. Applicable Item Types in Template Settings
This controls which line item types (e.g., products, services) the template supports — not the parent object like Opportunity or Quote.

D. Document Template object picklist
There is no picklist on the Document Template object that directly links it to Opportunity, Quote, or Order.

Object applicability is managed through the Applicable Objects field.