Which of the following best describes the term "gene flow"?

The term "gene flow" refers specifically to the movement of genes between populations, which occurs when individuals from one population migrate to another and breed. This exchange can introduce new genetic material into a population, impacting genetic diversity and potentially altering evolutionary trajectories. Gene flow is a critical mechanism in evolution, as it can counteract the effects of genetic drift and natural selection by promoting genetic variation among populations.

The other choices describe distinct biological concepts. The introduction of mutations refers to changes in the DNA sequence that can create new alleles, while the selection of traits that promote survival pertains to natural selection, where certain traits become more common in a population due to their advantages in a given environment. Adaptation focuses on how organisms change in response to environmental pressures over time, but it does not encapsulate the idea of gene movement between populations like gene flow does. Therefore, the definition provided by the correct choice accurately emphasizes the importance of interpopulation genetic exchange.