Answer:
(A) Nebula
Explanation:
The nebula is a cloud of gases such as hydrogen, helium, ionised gases and dust. A nebula is formed when remaining gas from another low mass star or gases in interstellar space condense together then the cloud of gases becomes so dense due to gravity to form the star. There are other types of nebula such as a supernova, which form due to the collapse of the star at the end of its life.