Sometimes advice comes cloaked as a contrite answer. Such is the way of the Navy. Look for a deeper meaning and move on.
Broadzilla gave you a great piece of advice for the interview, if not the Navy in general. FORGET how you did in Professor Winklebottom's Calc III class. Get ready to prove how you can deal with adversity and the unexpected. Start thinking about how you will get people to follow you to accomplish the business of a propulsion plant (hint: the Officer's crest on your hat isn't enough). Start thinking in terms of LEADERSHIP and less in terms of SCHOLARSHIP. Success at the senior levels depends on the former, not the latter.
If you are further interested in the specifics of the interview, shoot me a pm and I will give you my work email, and put you in touch with one of our newest O's on the ship. He will likely be glad to answer your question after I ask (

) him to do so.