Four point masses, each of value $\mathrm{m}$, are placed at the corners of a square $A B C D$ of side $\ell$. The moment of inertia through $A$ and parallel to $B D$ is

• A

  $\mathrm{m} \ell^2$
• B

  $2 \mathrm{~m} \ell^2$
• C

  $3 m \ell^2$
• Correct answer
  D

  $3 \mathrm{~m} \ell^2$

Hence, the correct answer is option: 'D'.