Which part of the diagram indicates the amplitude of the wave?

Answer : The rest position to the crest indicates the amplitude of the wave.

Explanation :

Amplitude of the wave : It is a wave that covers maximum amount of displacement on the medium from its rest position.

That means, the amplitude can be measured from rest position to the crest and also measured from rest position to trough.

Wavelength of the wave : It is the length of one complete wave cycle.

That means, the wavelength can be measured from crest to crest and trough to trough.

Hence, the rest position to the crest indicates the amplitude of the wave.

you have to draw the persons position over there