An aircraft is flying at a constant speed while in a steady climb. Which of the following statements is true about its total mechanical energy?

The total mechanical energy decreases because potential energy increases while kinetic energy remains constant.

The total mechanical energy increases because the aircraft gains potential energy while kinetic energy remains constant.

The total mechanical energy decreases because the aircraft loses speed during the climb.

The total mechanical energy remains constant because the increase in potential energy is offset by the constant kinetic energy.