A device known as an optical resonator is used in lasers. An optical resonator consists of an arrangement of mirrors that reflect electromagnetic radiation back and forth within an empty cavity. The electromagnetic radiation within the cavity reflects off of the mirrors multiple times. The mirrors are precisely placed so that only particular frequencies can survive within the cavity via constructive interference. All other frequencies are suppressed via destructive interference. The end result is a beam of light of a certain frequency.

An optical resonator of the type described above depends on the tendency of light to
A. behave as a wave.
B. excite atoms to certain energy levels.
C. excite electrons to certain energy levels.
D. behave as a particle.