Which statement is true about microevolution? a. it's evolution within a single population. b. it's evolution of small organisms. c. it's evolution within small populations.

The correct answer is option A.

Microevolution is the modification in the frequencies of alleles, which takes place over time within a population. This modification can be due to four distinct procedures, that is, selection (natural and artificial), mutation, genetic drift, and gene flow.

This modification takes place over a comparatively short duration in comparison to the modifications known as macroevolution that is where much larger distinctions in the population take place. Thus, the correct answer is that it is an evolution within a single population.