According to embryology, which three species have the closest common ancestor? insects, birds, and fish
amphibians, mammals, and birds
reptiles, amphibians, and bacteria
insects, bacteria, and reptiles

c. would be the answer : )

explanation:

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

gag reflex, poor dentition, gum retraction

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