What Evidence Now Exists for a Supermassive Black Hole at the Center

Multiple Choice

What evidence now exists for a supermassive black hole at the center of our Galaxy?

A) A very dark void in an otherwise bright region of space near the galactic center,indicating the presence of a black hole
B) Observations of intense inflow of matter toward the center of the Galaxy,as seen by light-Doppler-shifted toward the red-emitted by this matter
C) An absence of gas clouds surrounding the region of space near the galactic center
D) Very rapid motion of matter close to the nucleus of the Galaxy,requiring a very massive body to hold it in orbit