The answer is A. amplitude
The wave measure that is changing by the greatest amount in the image is amplitude. Amplitude is the height of a wave from its trough to its crest. In the image, the earthquake waves have a very large amplitude, indicating that they are releasing a lot of energy.
Wavelength is the distance between two successive crests or troughs of a wave. While the wavelength of the earthquake waves in the image is also changing, it is not changing as much as the amplitude.
Speed is the rate at which a wave travels. The speed of the earthquake waves in the image is not changing.
Frequency is the number of waves that pass a given point in space per unit time. The frequency of the earthquake waves in the image is not changing.
Therefore, the answer is A. amplitude.