The diagram above suggests that A.
geologic time periods occur in repeating cycles.
B.
geologic eras occur in repeating cycles.
C.
the Earth has not changed over geologic time.
D.
the Earth has changed over geologic time.

Aform of energy that is reflected or emitted from objects in the form of electrical and magnetic waves that can travel through space. there are many forms of  electromagnetic  energy including gamma rays, x rays, ultraviolet radiation, visible light, infrared radiation, microwaves and radio waves.