6- 7 if you can. i will give brainliest

Planets are generally larger than D. the other bodies in a solar system.
It is not the other answers because planets are smaller than stars, and they are within a solar system which is part of a galaxy.

Stars form in B. Nebulae.
Stars are born and formed within dense clouds of gas and dust. A common and well-known example of these dust clouds is the Orion Nebula. 

Hope I helped and the best of luck to you! I'll be rooting for you! :)

A. volume stays constant. just took took the quiz

The answer should be vaporization