Final answer:
The amplitude of an ansverse wave is the length from the midpoint to the crest.
Step-by-step explanation:
The amplitude of a wave is defined as the maximum displacement of the medium from its equilibrium position. It is the characteristic height of the wave. In the case of an ansverse wave, the amplitude is the distance between the equilibrium position and either the crest or the trough of the wave.
Therefore, the correct statement about the amplitude of any ansverse wave is option A: It is the length from the midpoint to the crest.