Retaking a course in which I got a C

Due to extenuating circumstances I did not perform as well as I could have in a major prep course. I was wondering how do UC’s (UCLA/CAL) look at it if I were to retake this course over even though I received a passing grade of a C?

You cannot retake a C grade. I mean, you can retake it, but you won’t get the units and the previous C will remain as the grade. You can retake a C- if the college has it set at lower than 2.0