You Have Just Returned from an Interview with a Company

Multiple Choice

You have just returned from an interview with a company and are considering the appropriateness of a thank-you letter or note.The thank you message is

A) not necessary if you thanked the interviewer in person before leaving the appointment.
B) appropriate and beneficial and should be written immediately.
C) appropriate and beneficial and should be written about two weeks from now if you haven't received a response from the company about the job.
D) not appropriate because it can be perceived as "pushy."