This is a comet. It is also called a dirty snowballs.
Many ways for example they look up related things and study them or they can test it and see what happens
The answer is C. nebular are star nurseries. When the massive gas being collapsing in its own weight. Local areas of gas begin to coalesce under gravity. Due to enormous pressure, nuclear fusion begins and a protostar is formed. The protostar grows into the sun as more hydrogen fuses at the core. The planetesimal materials at the edges of the protostellar discs coalesce to form planets that orbit the star.
