What Recent Evidence Seems to Indicate That Several Nearby Galaxies

Multiple Choice

What recent evidence seems to indicate that several nearby galaxies may contain supermassive black holes at their centers?

A) The rotation curve of these galaxies shows no decrease in orbital velocity of stars as the radius of orbit increases out to the observable limit of the galaxy, indicating an unusual source of gravity.
B) Spectroscopic observations of stars near the centers of these galaxies show extremely fast orbital velocities, indicating the presence of a large mass to keep stars in orbit.
C) Extreme redshift of light from stars near the centers of these galaxies is caused by gravitational redshift from a very massive object.
D) These galaxies are rushing rapidly toward each other (and in at least one case, toward the Milky Way!) because of the gravitational attraction among them.