Fertilization and development

Variation is most valuable when environmental conditions change because individuals may differ in their ability to survive and reproduce. A particular inherited variation, such as better tolerance of heat or disease, may help some members survive and pass that trait onward. Thus option A is correct. Identical organisms have fewer alternatives, and no offspring means variations cannot be inherited by a new generation.

Speciation generally requires separated populations to accumulate genetic differences over many generations. Different environments, mutations, natural selection and limited gene flow can make the groups increasingly distinct. If these differences eventually produce reproductive isolation, the populations may be recognized as separate species. Option A captures this gradual process. Immediate sameness, chromosome loss or permanent absence of reproduction would not explain the formation of a new species.

In flowering plants, fertilization is followed by development of the ovary into the fruit. The ovules contained inside the ovary become seeds, which is why option B is a tempting but incorrect distractor. Pollen grains are involved in pollination before fertilization, and the stigma receives pollen. Thus, the governing biological relationship is ovary to fruit and ovule to seed, making option A correct.