3. which of the following is a major part(s) of the cell theory?

a. all organisms are composed of one or more cells.

b. all cells that currently exist have originated from pre-existing cells.

c. cells are the most basic structural and functional unit of life.

d. all cells possess dna enclosed within a nucleus.

C

Explanation:

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:

they fuse to form they have half as many chromosomes as a somatic cell of the same individual. b