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.
<span>Inertia keeps us orbiting because any object with mass has the tendency to resist changes to their direction and speed of movement. Combine that with the interaction of the gravitational attraction of the sun, and that is what keeps Earth in orbit. The sun’s gravitational force is one that is proportional to Earth’s mass, and it acts in a way that is almost exactly perpendicular to Earth’s motion. This keeps Earth from spinning into the sun or far away from it.</span>
