Collisions Between Galaxies

Multiple Choice

Collisions between galaxies

A) do not occur because the distances between galaxies are so vast.
B) are relatively fleeting because galaxies move so rapidly and thus last only a few million years.
C) can last hundreds of millions of years.
D) have little long-term effect on the galaxies involved because gravity is a relatively weak force and the distances over which it must act between galaxies are so great.