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

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

Explanation:

Stars are born in stellar nurseries known as nebula. Sun, the star at the center of the solar system was born in the solar nebula.

Nebula is a molecular cloud of dust and gases. Due to gravity, this cloud collapses under its own weight and condenses to form the core. It gathers more mass till the temperature of the core rises enough to start the nuclear fusion reaction. A star is born then.

the answer would be c. motion and direction

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