Question

A star is said to be born when _____.

A) pressure within a protostar becomes so great that a supernova occurs
B) a protostar reaches a temperature high enough for nuclear fusion to begin
C) a red giant collapses on itself and becomes a black hole
D) a dark, cool interstellar cloud begins to contract

Answer 1

A protostar reaches a temperature high enough for nuclear fusion to begin Description

Answer 2

Option (B)

Step-by-step explanation:

A star is usually said to be born when atoms of lighter elements are subjected to high compression under the influence of high pressure and temperature condition and also due to the gravitational collapsing of interstellar particles, that allow the nucleus of the atom to undergo the process of fusion. This leads to the release of a significantly large amount of energy in all directions.

In simple words, these stars result from the gravitational collapsing of the clouds of interstellar particles such as gases and dust particles.

The luminosity of a star depends on the amount of hydrogen gas it contains, which undergoes fusion by nuclear reaction process.

Thus, the correct answer is option (B).