As a non-science undergrad major, my first few sciences classes were a DISASTER! I didn't have the best professors and by the time I got to ochem, I couldn't handle another C. I decided to retake them, as I knew C's were not going to get me far...I met a chemistry professor who just made Chemistry EASY to understand. I ended up retaking all my chems (yes General chemistry 1, 2 and Ochem1) because I knew I had to boost my GPA. Although it does not replace the original grade, it will boost your GPA and you will gain better understanding of the material (which I believe matters when it comes to taking the OAT). If you can retake the class, then do it. But just be advised, just because you take it at community will not make it easy. I have found, especially with the community colleges in LA, they use the science community college classes to filter students out...so it will still take studying to get that A!