Final answer:
The parent plants are heterozygous for pea color.
Step-by-step explanation:
The best answer for this question is option C. The parent plants are heterozygous for pea color. Heterozygous means that the parent plants have different alleles for pea color: one dominant allele and one recessive allele. In this case, the dominant allele determines the yellow pea color while the recessive allele determines the green pea color. Since most of the offspring have yellow peas, it can be inferred that the dominant yellow allele is more common in the cross.
Learn more about Punnett Square