What is meant by "elastic collisions"?

A.) heat given off by constant collisions

B.) compression of the gas

C.) resultant force of all combined collisions

D.) collisions and rebounds without loss of energy

I believe D I know there is no net loss of kinetic energy

D. Elastic just means they collide and then bounce off of each other sort of like billiard balls. Inelastic collision is more like what happens in a car crash. The cars don't bounce off of each other, they get crushed