Which of the following best describes the dust, gas, and celestial bodies of the Milky Way Galaxy?

A. The faster they move, the less gravity they experience.
B. They experience gravity only if they have significant mass.
C. The farther away they are from the center of the galaxy, the more they are pulled by gravity
D. They orbit around the center of the galaxy because of gravity.

D. They orbit around the center of the galaxy because of gravity.