Question

what is a nebula? the core of a massive star a cloud of gas and dust in space a swirling disk with a lot of gravity the debris remaining after a supernova

Explanation:

A nebula is an interstellar cloud made up of gas (mostly hydrogen and helium) and dust. It can be a site of star - formation. The other options describe different astronomical objects or phenomena.

Answer:

B. a cloud of gas and dust in space