At the center of the Milky Way galaxy lies a black hole.
The correct answer is "a black hole." At the center of the Milky Way galaxy, there is a supermassive black hole called Sagittarius A*. To arrive at this answer, one can use various sources of information such as scientific research, astronomical observations, or educational websites. These sources provide data and studies conducted by experts in the field of astrophysics. By referring to these trusted sources, one can confidently state that a black hole is located at the center of the Milky Way galaxy.
