The unit of rotational inertia of a body in C.G.S system is A. cm4 B. kg.cm2 C. gm.cm2 D. gm.cm3

The correct answer is C. gm.cm2.

Rotational inertia is the resistance of an object to changes in its rotation. It is measured in units of kilogram-meters squared (kg m2). However, in the CGS system, the unit of mass is the gram (g) and the unit of length is the centimeter (cm). Therefore, the unit of rotational inertia in the CGS system is gram-centimeters squared (g cm2).

Option A is incorrect because it is not a unit of rotational inertia. Option B is incorrect because it is the unit of mass in the SI system, not the CGS system. Option D is incorrect because it is the unit of volume in the CGS system, not the unit of rotational inertia.