C.D.
You say that she is making B's and C's and you have punished her?
She is 13 and at a rough age and grade in school. I would understand if her grades were D's and F's and you punished her.
All you are doing is making her feel that that is not enough and she is not pleasing you.
You may disagree, I have a 14 year old son and I did that also. But then I saw the effect that it had on him. So I relaxed and did not punish him the next time that he had a C and it worked. His grades went up and there were not as many problems at home with him being angry.
C.