Which one of the following is a fallacy?

Question

$\begin {array} {1 1} (A)\;\text{The elements on the main diagonal of a symmetric matrix are all zero.} \\ (B)\;\text{The elements on the main diagonal of a skew-symmetric matrix are all zero.} \\ (C)\;\text{For any square matrix $ A, \large\frac{1}{2}(A+A’)$  is symmetric}\\ (D)\;\text{For any square matrix  $A, \large\frac{1}{2}(A-A’)$  is skew-symmetric.} \end {array}$