Astronomers have seen stars forming within a nebular cloud. as the nebular cloud condenses and its own gravitational attraction collapses it, heat and energy build up creating

nuclear fusion

Explanation:

Nuclear fusion is a stage that happens during star formation. This begins in the gravitational collapse of a giant nebula cloud. These clouds can span several dozen cubic light years of space and contain large amounts of matter. When gravity collapses the cloud, heat and energy accumulate, the cloud splits into smaller pieces, each centered around a concentration of matter. As these concentrations increase in mass, gravitation corresponds, and with it the whole process accelerates, with the collapse itself creating thermal energy.

Eventually, these parts condense under heat and pressure into gaseous spheres called proto-stars. If a proto-star does not concentrate enough mass, it never reaches the pressure and heat necessary for nuclear fusion, and becomes a brown dwarf.

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

explanation:

the answer is false?