Which energy transformations best illustrates why people can walk? a) chemical energy is being converted into light energy. b) chemical energy is being converted into thermal energy. c) chemical energy is being converted into mechanical energy. d) chemical energy is being converted into more chemical energy.

The answer is letter c.

The explanation behind this is when human consumes a plant or when a human being eats an animal that ate a plant. The chemical energy kept in the plant (or animal) cells is progressed into the cells of the human's body. All of the body progressions, like ingestion, breathing, pumping blood, are driven by cells changing the kept chemical energy into heat and work, in a procedure called respiration. In the muscle cells of the human (or any animal), the chemical energy is converted into mechanical work and heat. The muscle pacts, the legs thrust, and the body jumps into the air. 

d is the answer i came up with

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.