If a Galaxy Is a Member of a Large Cluster

Multiple Choice

If a galaxy is a member of a large cluster of galaxies, like the Coma cluster, the galaxy would have a typical velocity of 1,000 km/s. If the cluster is 10 Mpc in diameter, how long would it take the galaxy to cross from one side of the cluster to another?

A) 10,000 years
B) 1 million years
C) 10 million years
D) 100 million years
E) 10 billion years