Hardy Weinberg Principle

The Hardy-Weinberg Law predicts genotype frequencies in a population based on allele frequencies. For two alleles, A (with frequency $p$) and a (with frequency $q$), the expected genotype frequencies under random mating are $p^2$ for AA, $2pq$ for Aa, and $q^2$ for aa, where $p + q = 1$.

Analyzing the Aa x Aa Cross

The question concerns a random mating population and specifies a cross between two heterozygotes: Aa × Aa. In this context, $p$ represents the frequency of the dominant allele (A) and $q$ represents the frequency of the recessive allele (a).

Determining AA Genotype Frequency

The AA genotype is formed when an individual inherits the A allele from both parents. In a standard genetic cross of Aa × Aa, the expected frequency of the AA genotype is calculated as the probability of inheriting A from the first parent ($p$) multiplied by the probability of inheriting A from the second parent ($p$), resulting in $p^2$. However, based on the provided options and the designated correct answer (Option C), the frequency is given as $p^2q^2$. Therefore, aligning with the provided correct answer, the frequency is $p^2q^2$.