As a rock falls, some of its potential energy is transformed into kinetic energy. What is true about the mechanical energy during this transformation?
A.
It decreases because potential energy is a kind of mechanical energy.
B.
It does not change because kinetic energy and potential energy are both kinds of mechanical energy.
C.
It increases because kinetic energy is a kind of mechanical energy.
D.
It does not change because kinetic energy and potential energy are not kinds of mechanical energy.