The answer is B. Since the first collision is elastic, both momentum and kinetic energy can be conserved within the system. The coefficient of restitution for an elastic collision is one, and it is often referred to as a perfectly elastic collision. Conversely, in a perfectly inelastic collision, kinetic energy is lost as it transforms into another form, such as internal energy. While momentum remains conserved in an inelastic collision, kinetic energy is not.
