The moment of inertia of the system of four spheres about the side AD, when four solid spheres each of mass m and radius r are located with their centers on four corners of a square ABCD of slide a is :

Question

$\begin{array}{1 1} \frac{2m}{5} (2r^2+5a^2) \\\frac{m}{5} (7r^2+5a^2) \\ \frac{2m}{5} (4r^2+5a^2) \\ \frac{m}{5} (3r^2+5a^2) \end{array} $