Which three types can be used as @Controller method arguments?

A. Locale

This is true because the Locale argument can be used to resolve the current locale that the client is using, based on the Accept-Language header or a cookie1.

B. Principal

This is true because the Principal argument can be used to access the currently authenticated user, if any1.

F. HttpSession

This is true because the HttpSession argument can be used to access the current session, if any1. Note that this argument is not required and will be null if a session does not exist.