Answer:
One allele is on one chromosome, and the other is in the same position (locus) on the homologous chromosome.
Explanation:
The genotype of an organism refers to the genetic makeup or complete set of genes. The genes control the trait of an organism and exist in an organism in their alternative form called alleles.
Since the alleles are the alternative form of a gene, therefore, they must be present at the same position called a locus.
These alleles are present on the homologous chromosome in which each homologous chromosome is contributed by each parent.
Therefore when the genotype is aa then a and a allele will be present on homologous chromosomes in the same position.
Thus, the selected option is correct.
