Should I get a C in class, or a D and retake to get an A?

I am not going to explain why I got this grade. The situation is I calculated my grades and am only able to pull of a C in my calculus class. Should I purposely get a D to retake the class and get an A. I want to transfer to UC Berkely, and you need a pretty high GPA. It says :Transfer applicants need B grades or better in technical courses to be adequately prepared to continue with junior year course work:" So what do you think?