Which wave has the lowest amplitude

The wave marked with the purple line is the wave that has the lowest amplitude.

The wave amplitude represents the vertical distance between the wave's peak or valley, and the equilibrium point.

To put in other words, the wave amplitude can be defined as the maximum displacement between of the points on the wave.

The wave amplitude is one of the most important parameters of the waves.

When the waves are show in the manner as in this image, the simplest way to determine which one has the highest and which one has the lowest amplitude,  is to watch which one is having the biggest distance and which is having the smallest distance from the equilibrium line when they are at their peak or valley.

The wave marked with the purple line

Explanation:

d: social contract theory

i believe the answer is d.