Supermassive Black Holes Are Believed to Be Located at the Center

Multiple Choice

Supermassive black holes are believed to be located at the center of many galaxies because

A) the rotation curve of the galaxy indicates that 90% of the galaxy is dark matter.
B) the orbital motion of material near the center is very fast and indicates a very massive core.
C) the shape of the bulge in all spiral galaxies can only be supported by a supermassive black hole.
D) the spiral structure requires a black hole to maintain the spiral arms.
E) the orbital speeds of a globular clusters in the galaxy are greater than the speed of light.