A car starts at the top of a hill with 200 J of energy, and rolls down a frictionless surface. The isolated system consists of the car, hill, and earth. What happens to the energy of the system as the car moves down the hill?

The total energy stays the same but is converted from being stored as kinetic energy into elastic potential energy as it moves.

The total energy stays the same but is converted from being stored as gravitational potential energy into kinetic energy of the car as it moves.

The total energy decreases and is converted from being stored as gravitational potential energy into kinetic energy as it moves.

The total energy decreases and is converted from being stored as elastic potential energy into kinetic energy as it moves.