What does p² in the below mentioned Hardy-Weinberg equation indicate? (p+q)² = p² + 2pq + q²

The correct option is "individuals that are homozygous dominant".

To understand why this is correct, let us break down the Hardy-Weinberg equation step-by-step:

The Hardy-Weinberg principle describes a state of genetic equilibrium in a diploid population. For a gene with two alleles, say A (dominant allele) and a (recessive allele), we define their frequencies as follows:
- Let $p$ represent the frequency of the dominant allele (A).
- Let $q$ represent the frequency of the recessive allele (a).

Since these are the only two alleles for this gene in the population, their frequencies must sum to 1:
$p+q=1$

To find the frequencies of the resulting genotypes in the population, we square both sides of the equation:
${(p+q)}^2=1^2$
Expanding this algebraic expression gives the Hardy-Weinberg equation:
$p^2+2pq+q^2=1$

Each term in this expanded equation represents the frequency of a specific genotype in the population:
- $p^2$ represents the frequency of the homozygous dominant genotype (AA). This is the fraction of the population that inherits the dominant allele from both parents.
- $2pq$ represents the frequency of the heterozygous genotype (Aa).
- $q^2$ represents the frequency of the homozygous recessive genotype (aa).

Therefore, in the Hardy-Weinberg equation, $p^2$ specifically indicates the frequency of individuals that are homozygous dominant.