In Hardy-Weinberg equilibrium, which equations relate allele and genotype frequencies?

• A. p + q = 1 and p^2 + 2pq + q^2 = 1
• B. p^2 + q^2 = 1
• C. p + q = 2 and p^2 + q^2 = 1
• D. p^2 + q^2 + 2pq = 3

Answer: (A)