A rigid body, under the action of external forces, can be replaced by two masses placed at a fixed distance apart. The two masses form an equivalent dynamical system, if

• A. The sum of the two masses is equal to the total mass of body
• B. The sum of mass moment of inertia of the masses about their center of gravity is equal to the mass moment of inertia of the body
• C. All of these
• D. The center of gravity of the two masses coincides with that of the body

Answer: (C)