Which mechanism(s) are responsible for introducing new alleles into a population's gene pool? a) gene flow b) emigration c) niche shift d) natural selection

The right answer is -

A) Gene flow

Explanation:

Gene flow is a process of gene migration or the transfer of gene variant (also called allele, which is responsible for genetic variation in population) from one population to another population.

As a consequence of gene migration, new alleles are introduced or added in the already existing population, thereby increasing genetic diversity.

Thus, option A) is the right answer.

covalent bonding is a form of chemical bonding between two non metallic atoms which is characterized by the sharing of pairs of electrons between atoms and other covalent bonds.