Abike rider does work to get to the top of a mountain. how could you use the law of conservation of energy to describe his trip down the mountain? a. the rider uses energy to do work going up the mountain. b. this energy is converted to potential energy and then changes into kinetic energy on the way down. c. the bike rider's stored chemical energy allows him to move down the mountain, storing more and more energy as he goes. d. the bike rider gains electrical energy going up, which changes into electromagnetic energy on the way down.