Is Space Expanding Within Clusters of Galaxies

Is space expanding within clusters of galaxies?

A) No, because the universe is not old enough yet for these objects to have begun their expansion.
B) No, because their gravity is strong enough to hold them together even while the universe as a whole expands.
C) No, because expansion of the universe affects only empty space, not space in which matter is present.
D) Yes, and that is why clusters tend to grow in size with time.