Final answer:
Galaxies are moving away from Earth with their speed increasing with distance, such that the farther a galaxy is, the faster it is receding. To rank galaxies by speed, order them from closest to farthest, with the farthest moving the fastest.
Step-by-step explanation:
Based on the provided information, the recessional velocity of galaxies increases with their distance from Earth due to the expanding universe phenomenon. This relationship, observed as galaxies flying apart from one another, is a foundational piece of evidence supporting the Big Bang Theory. The speed at which a galaxy is moving away from Earth can be measured by the Doppler shift of light. If a galaxy is farther away, it will have a higher recessional velocity, and thus, will be moving faster.
To rank four galaxies by their speed moving away from Earth, one would arrange them from the one that is closest to the one that is farthest. The galaxy closest to us would have the slowest speed, and the one farthest away would have the highest speed, nearly approaching the speed of light. The order would be A, B, C, D, with A being the closest and slowest and D being the furthest and fastest, assuming the galaxies are listed from nearest to farthest from Earth.