Four point masses, each of value $m$, are placed at the corners of a square ABCD of side $l$. The moment of inertia of this system about an axis passing through A and parallel to BD is :

Question

( A ) $2\; ml^2$
( B ) $\sqrt{3}\; ml^2$
( C ) $3\; ml^2$
( D ) $ml^2$