Final answer:
In Mendel's experiment with pea plants, the F2 generation consists of 25 percent green and 75 percent yellow seeds.
Step-by-step explanation:
In Mendel's experiment with pea plants, the F2 generation results from crossing the F1 generation offspring. The F1 offspring are all yellow seeds since yellow color is dominant over green.
When the F1 offspring are crossed with each other, there is a 25% probability of both parents contributing a green allele, resulting in offspring with green seeds, and a 75% probability of both parents contributing a yellow allele, resulting in offspring with yellow seeds. Therefore, the correct answer is d. 25 percent green, 75 percent yellow seeds.