Whats wrong with a B in physics. I got a B in physics and worked my butt off for it. Had 20 people in the first day of class, at the end there were 8 of us, myself include, 7 of us by the way, women. I got that B and I am proud of it. Retake it if you want, but if I were you, I would concentrate my efforts on my other pre-reqs.