Thanks for your reply.
I would like to gain a better understanding of the subject however my main reason for wanting to retake the class is to become more marketable I suppose. And as you said, I don't need to retake the class to better my understanding.
If this was a first-year or a sophomore...
I'm in a physics program going onto my final year of study. My cGPA is currently 4.01 (on a 4.3 scale) however during my second year, I took an upper year math class on Graph Theory and performed very poorly in it, I got a C- (roughly 63-66%). I'm hoping to apply to graduate schools come next...