Which of the following equations correctly represents the law of cosines?

A. 2 = 22 + b2 - 2ab.cos(B)
B. 2 = 22 + c2 - 2ac.cos(C)
C. a2 = b2 + c2 - 2bc.cos(A)
D. b2 = 22 +62 - 2bc.cos(B)