One kind of potential energy is elastic potential energy. This is the kind of energy present in a rubber band that is stretched. When the rubber band is released, the elastic potential energy is converted to kinetic energy. Elastic potential energy is also present in a muscle that is contracted, or tensed.

The diaphragm is a large muscle that is used to breathe. Contracting the diaphragm causes air to move into the lungs. When the diaphragm is relaxed, air moves out of the lungs as _______ is converted to kinetic energy.
A.
chemical potential energy
B.
light energy
C.
elastic potential energy
D.
heat energy