Explanation:

Two ways that a developer can deploy some small CSS changes without waiting for the entire project deployment are right-clicking the folder for the component and choosing Deploy Source to Org and right-clicking the CSS file that was edited and selecting Deploy Single File. Deploying source to org is a way of deploying metadata from a local project to an org using Salesforce CLI commands. The developer can use Visual Studio Code to execute these commands by right-clicking on files or folders in the project and choosing from various deployment options. Right-clicking the folder for the component and choosing Deploy Source to Org allows the developer to deploy only the files that belong to that component, such as HTML, JavaScript, CSS, and XML files. Right-clicking the CSS file that was edited and selecting Deploy Single File allows the developer to deploy only that CSS file and not any other files in the project. These options can save time and bandwidth for deploying small changes without affecting other components or files in the project.

Modifying the StoreIntegratedService to map to an Apex class ID using Workbench is not a way of deploying CSS changes, as it is only used for registering internal services that are provided by Salesforce B2B Commerce out-of-the-box. Entering the integration class name and version in store administration is not a way of deploying CSS changes either, as it is only used for selecting an existing integration class that has already been registered as an external service.

Salesforce References:

Salesforce CLI Command Reference: force:source:deploy, Salesforce Developer Tools for Visual Studio Code, B2B Commerce Developer Guide: Integration Framework, B2B Commerce Developer Guide: RegisteredExternalService Object