When pushing a child on a swing, you must give them a push periodically to keep them moving. This seems to go against the law of inertia and the conservation of energy.

When pushing a child on a swing, you must give them a push periodically to keep them moving. This seems to go against the law of inertia and the conservation of energy. Why does the child need a push periodically to keep moving.

A) Energy is lost over time slowing down the swing.
B) All objects will naturally come to rest over time.
C) A wind must have been blowing in the opposite direction.
D) Friction provides an outside force slowing the swing down.