In population genetics, gene flow is best defined as which of the following processes affecting allelic frequency changes?

• A. A random change in allele frequencies due to sampling error, strongest in small populations
• B. The movement of alleles between populations through migration of individuals or their gametes, altering allele frequencies
• C. A consistent increase in the frequency of the most fit allele due to differential survival and reproduction
• D. A change in allele frequencies caused by new mutations arising in a population over time

Answer: (B)