The Center of Our Galaxy Contains a Very Intense Source

The center of our galaxy contains a very intense source of radio and X-ray radiation named Sgr A*. What is it about this source that supports the idea that the radiation comes from a black hole?

A) The radiation is strongly blueshifted, indicating that the object is collapsing.
B) The radiation is strongly redshifted indicating that the object is growing.
C) The radiation is coming from an incredibly small object.
D) Radio waves can only be produced by matter orbiting a black hole.
E) Only radiation from a black hole could penetrate the giant molecular clouds between Sgr A* and Earth.