Answer:
B, but see below
Step-by-step explanation:
Remark
As far as I can see, B and C are the same except that B uses a period and C uses a comma. I would say that C is incorrect. C creates a run on sentence.
A is correct. So you have to choose between A and B correct. It is a matter of choice since grammatically both are correct.
I think you are intended to choose B