The diagram below shows two longitudinal waves, wave X and wave Y, at one instant of their motion. Each oval represents a particle acted on by the energy of the wave as it moves from left to right. The number of ovals carrying wave X is equal to the number of ovals carrying wave Y.

Comparing the two, it appears that wave X has a greater _______ than wave Y.
A.
period
B.
wavelength
C.
frequency
D.
amplitude