How many possible genotypes and phenotypes are there for a single gene trait that shows dominance in any given population? a) one genotype, one phenotype b) two genotypes, two phenotypes c) three genotypes, two phenotypes d) two genotypes, three phenotypes

For a single gene trait that shows dominance in any given population, three genotypes and two phenotypes are possible.

Let us assume that the dominant single gene trait is represented by A. Genes always exist in alternate pairs or alleles.

Thus, there are 3 possible genotypes while only 2 phenotypes are possible from a single gene trait that shows dominance.

More on dominance/recessive can be found here:

the answer to your question is:

c. complementary base-pairing