Answer:
Black holes:
A are the brightest objects in space.
B are the most well understood objects in space.
C pulse in a regular pattern.
D None of the choices are correct.
Step-by-step explanation:
A black hole is a region of space where the pull of gravity is so strong that nothing can escape. It's a "hole" in the sense that things can fall in, but not out of it. It is "black" in the sense that not even light can escape.
I hope I helped you! :)