Question

Which of the following describes a major role of gravity in star formation?
A.
Gravity compresses gases at the center of a solar nebula until temperatures are high enough for nuclear fusion to occur.
B.
Gravity causes an interstellar cloud fragment to expand rapidly until it is large enough to form a star at its center.
C.
Asteroids passing by a solar system are pulled in by planets' gravities to form a star at the center of the solar system.
D.
The gravitational forces of planets push gases from their atmospheres to form a star at the solar system's center.

Answer 1

A. Gravity compresses gases at the center of a solar nebula until temperatures are high enough for nuclear fusion to occur.

Explanation: Gravity causes an interstellar cloud (or solar nebula) to collapse, concentrating mass and raising temperature and pressure in the center until a protostar ignites nuclear fusion.