A cross among individuals with contrasting variations at one locus for the attribute is called a monohybrid cross. Each parent provides one type of allele or a trait to their offspring.
Monohybrid cross can be shown using the Punnett square, to determine the probability of a progeny expressing that genotype.
The correct answer is :
Option C. Box 1 and box 3
The reason for the answer is:
1. Box 1 will produce offspring with genotype: Aa
2. Box 2 will produce offspring with genotype: aa
3. Box 3 will produce offspring with genotype: Aa
4. Box 4 will produce offspring with genotype: aa
Therefore, Box 1 and Box 3 represents heterozygous alleles, whereas box 2 and box 4 represents purebred alleles.
To learn more about purebred and heterozygous follow the given link:
https://brainly.com/question/13050360