Consider the following two statements:
A. linear momentum of the system remains constant.
B. Centre of mass of the system remains at rest

Options

A. A implies B and B implies A
B. A does not imply B and B does not imply A.
C. A implies B but B does not imply A
D. B implies A but A does not imply B

Answer

D

Explanation

If CM is at rest, it definitetlyy means momentum of hte system is constant. But momentum of the system is constant, it does not mean center of mass is at rest.