B
Below is a question with multiple-choice answers. Choose the correct option based on your reasoning.

### Question:
The human body produces motion by changing chemical energy into mechanical energy. Which of these best describes what happens to the energy?

### Choices:
A. The total amount of energy increases.
B. The total amount of energy is constant.
C. The energy is destroyed through motion.
D. The amount of chemical energy increases.

### Answer:
