What Is the Great Attractor

What is the Great Attractor?

A) a supermassive black hole at the center of the Milky Way Galaxy
B) an immense black hole thought to be at the center of the universe and a remnant of the cosmic singularity
C) a large collection of mass about 50 Mpc from Earth in the direction of the Hydra-Centaurus supercluster toward which the Local Group of galaxies is being drawn
D) an immense black hole somewhere in the universe from the accretion disk of which the cosmic 3-K background radiation is believed to be emitted