A solid sphere of uniform density and radius 4 units is located with its centre at the origin O of coordinates. Two spheres of equal radii 1 unit with their centres at A(? 2, 0, 0) and B(2, 0, 0) respectively are taken out of the solid leaving behind spherical cavities as shown in figure [IIT 1993]

• A. The gravitational force due to this object at the origin is zero
• B.             The gravitational force at the point B (2, 0, 0) is zero
• C.             The gravitational potential is the same at all points of the circle \[{{y}^{2}}+{{z}^{2}}=36\]
• D.             The gravitational potential is the same at all points on the circle \[{{y}^{2}}+{{z}^{2}}=4\]