Which best describes the wavelength of a simple wave?

A. The distance from the crest of a wave to the crest of the
next wave
B. The distance from the crest of a wave to the trough of the
next wave
C. The number of waves that pass a certain point in a minute
D. The speed at which the wave travels in m/s

I think it is A

Explanation: Wavelength is the distance from one crest to another, or from one trough to another, of a wave (which may be an electromagnetic wave, a sound wave, or any other wave). Crest is the highest point of the wave whereas the trough is the lowest.

an obstruction

myth. it was once thought that animals, including cats and dogs, could only see in black and white. however, scientists have proven this to be a myth. in all animals, including humans, the perception of colour is determined by the presence of cells in the eye called cone photoreceptors.