A spherical shell has inner radius $R_1,$ outer radius $R_2,$ and mass $M,$ distributed uniformly

throughout the shell. The magnitude of the gravitational force exerted on the shell by a point

mass particle of $m,$ located a distance $d$ from the center, inside the inner radius, is:

A$.0$

B$.GM\frac{m}{R_1^2}$

C$.GM\frac{m}{d^2}$

D$.GM\frac{m}{R_2^2-d^2}$

E$.GM\frac{m}{(R_1-d{)}^2}$

ans: A