It should be natural selection since there is no external influence implied. (like environment or genetic mutations.)
Answer:
i can only define the terms for you.
Explanation:
chromosome - a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
chromatid - each of the two threadlike strands into which a chromosome divides longitudinally during cell division, each containing a double helix of DNA.
gene - a distinct sequence of nucleotides that forms a part of a chromosome, the order of which determines the order of monomers in a polypeptide or nucleic acid molecule which a cell or virus that may synthesize
Well it helped the animals and humans grow the population.
