Which of the following decribes a properly controlled experiment?

Two pea plants with yellow peas are crossed. most of their offspring have yellow peas, but about 25 percent of the offspring have green peas. for pea color, yellow is the dominant trait and green is the recessive trait. what does this tell you about the two parent plants? a. the parent plants have only dominant alleles for pea color. b. the parent plants are heterozygous for pea color. c. pea color follows an incomplete dominance pattern of inheritance. d. the parent plants are homozygous for pea color.