An object, mass 1,0 kg, moving at 6,0 m s-1 to the right makes an elastic collision with an object, mass 2,0 kg, initial

[correctanswer]

An object, mass 1,0 kg, moving at 6,0 m s-1 to
the right makes an elastic collision with an object, mass 2,0 kg,
initially at rest. Assume that the objects are moving on a smooth
horizontal surface. You are looking for the speed of the 2,0 kg
mass after the collision. What is the overarching physics
principle(s) (or law) that addresses (or solves) the following
situation
Conservation of momentum only
Conservation of mechanical energy
Conservation of momentum and kinetic energy
Conservation of kinetic energy only
Newton's second law
Kinetic energy