Let M and N be two $$3 \times 3$$ non-singular skew-symmetric matrices such that $$MN = NM$$. If $$P^T$$ denotes the transpose of P, then $$M^2N^2(M^TN)^{-1}(MN^{-1})^T$$ is equal to

A

$$M^2$$

B

$$-N^2$$

C

$$-M^2$$

D

$$MN$$