Under many conditions, the center of mass of a system of particles can represent the system as a whole. But how far does this rule extend?

Consider two identical particles traveling toward each other at the same speed. By examining this system, choose the correct response.

a. The momentum and kinetic energy of the center of mass is equivalent to that of the system of particles.
b. The kinetic energy, but not the momentum, of the center of mass is equivalent to that of the system of particles.
c. Neither the momentum nor the kinetic energy of the center of mass is equivalent to that of the system of particles.
d. The momentum, but not the kinetic energy, of the center of mass is equivalent to that of the system of particles.