Why are trophic levels important?

Why reason best illustrates why hershey and chase chose to use viruses in their 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.

Can someone me i need the answer and don’t understand?