Trust me I had a few C's on my transcripts as well. The two interviewers I had made the interview similiar to a conversation. They asked a question and then I followed with a question. I thought this was the way to go, and at the end of the interview they commended me for asking a lot of questions. Remember it's an interview for the dental school as well. As for my grades, I had the Biochem professor (Dr. B) at MD, he saw that I received a C in Biochem. He wasn't to pleased, so he proceeded to ask me numerous questions about Biochem. which I nailed. In the end, I impressed him with my ability to comprehend the material even though I didn't receive the grade I thought I deserved (which was B). Just be able to explain why you received the grades you received. The interview was very laid back. If you really wanna know how laid back the interview was here's what happened in my interview in Sept. The Biochem professor asked me a question about fatty acids in foods, since I was a double major (Bio and Food Science) I nailed the answer and said that was a well thought out answer. In return I said "I'm glad I paid attention during that class." He laughed and said I like you. I figured what did I have to lose. Good luck with your interview.