Which factor would disrupt Hardy-Weinberg equilibrium?

• A. Large population size
• B. Non-random mating
• C. Random mating
• D. No mutation

Answer: (B)

Hardy-Weinberg equilibrium stays constant across generations only when certain conditions hold, including random mating. When mating is not random, the way alleles combine into offspring changes the genotype proportions. This shifts the observed frequencies away from p^2 : 2pq : q^2, even if the underlying allele frequencies stay the same, so the population is no longer in equilibrium. The other factors listed don’t inherently disrupt the balance: a large population minimizes drift, random mating is the required condition for equilibrium, and no mutation means no new alleles are introduced. So non-random mating is the factor that disrupts Hardy-Weinberg equilibrium.