Respuesta :

A would be the wavelength, C would be a crest, D would be the amplitude, leaving B which is the trough.

Answer: B. B

Explanation:

The trough is B because it is the "minimum" amplitude of a wave since amplitude is D which is the displacement of wave from its initial position. The minimum value of the amplitude will be at B which is the trough.

Note that the maximum value of the amplitude will be the crest which at C.