Astar 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

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

Option (B)

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).

answer: angiosperms

dicots

angiosperms are highly evolved plants, they produce seeds which are enclosed within in a carple. these are the largest group of plants on earth. they include trees, shrubs, herbs and small flowering plants. angiosperms exhibit a flowering stage in their life cycle. the flower serves the function of reproduction and fruit formation in majority of angiosperms. dicot is the term used to describe flowering plants that have two seed leaves. dicots are plants which develop seeds which split into two parts called cotyledons. each cotyledon contains one embryo.

here, a small purple flower development indicates that the plant belongs to angiosperms and having two embryonic leaves indicates it belongs to dicots.