https://help.salesforce.com/articleView?id=named_credentials_define.htm&type=5

Login flow

B is correct

The correct answer is B. Handle authentication in the code.

In this scenario, where an Architect is required to integrate with an External Data Source via an Apex callout, authentication is achieved by handling it in the code. This is because the Named Credential in Apex callouts only provides a secure way of storing the authentication credentials for the external system, but does not automatically handle the authentication process.

The architect must write the code to handle the authentication process, typically by including the authentication credentials in the callout request headers, or using a specific authentication protocol such as OAuth.

I think B is the correct answer

"C" cannot be right. Via code, the "authentication" is handled by referencing the named credential in the callout URL. Salesforce Connect is data virtualization.