Final answer:
The law of conservation of energy states that the total energy in the universe remains constant.
Step-by-step explanation:
The subject of this question is Physics. The law being referred to is the law of conservation of energy.
The correct option is C. Total energy is constant. According to the law of conservation of energy, although energy can be converted from one form to another, the total amount of energy in the universe remains constant. Energy cannot be created or destroyed, only transformed.
For example, consider a roller coaster. The potential energy of the coaster at the top of a hill is converted into kinetic energy as it moves downhill. The total energy of the coaster remains constant throughout the entire ride.