Question

which is shown by the letter x?
trough
amplitude
crest
wavelength

Explanation:

In a wave - diagram, the trough is the lowest point of the wave, the amplitude is the distance from the rest position to the crest or trough, the crest is the highest point of the wave, and the wavelength is the distance between two consecutive identical points (such as two crests or two troughs). The letter X in the given diagram points to the highest point of the wave.

Answer:

C. crest