C is the most likely answer to this question.
Exactly how many chromosomes we are talking about depends on the species. A mosquito has 6 chromosomes, a pea plant has 14, a sunflower 34, a human being 46, and a dog 78. Closely related species tend to have a similar number of chromosomes.
I believe the answer is comparative anatomy. It is the study of the similarities and differences in the structures of different species. Similar body parts may be homologies or analogies, such that both provide evidence of evolution. Similarities in embryos are evidence of common ancestry. For example all vertebrates embryos have gill slits and tails.
