What Is a Central Dominant Galaxy

What is a central dominant galaxy?

A) a galaxy around which many other smaller galaxies orbit
B) a giant spiral galaxy that exerts large tidal forces on other nearby galaxies
C) a spiral galaxy from which many smaller galaxies form when it is stripped apart by tidal forces
D) a giant elliptical galaxy at the center of a dense cluster
E) a hypothesized galaxy type that no longer exists but once dominated the structure of the universe