When an object such a a stone is dropped into water, it disturbs the surface of the water. Waves form at the surface of the water and travel outward from the point of the disturbance. The diagram below is based on a single frame from a video of the waves that formed when a stone was dropped into water.

If a student were to measure the distance labeled as "Z," she would know the value of the of the wave.
A.
radius
B.
amplitude
C.
frequency
D.
wavelength