The correct answer is D. Endosperm.
The endosperm is a nutritive tissue that develops within the seed of a flowering plant. It is triploid, meaning that it contains three sets of chromosomes. The endosperm is produced by the fusion of a haploid sperm cell with two haploid polar nuclei in the embryo sac. The endosperm provides nutrients to the developing embryo until it is able to photosynthesize on its own.
The ovule is the female reproductive structure of a flowering plant. It is located in the ovary and contains the female gamete, the egg cell. The ovule develops into a seed after fertilization.
The zygote is the cell that is formed when the sperm cell fertilizes the egg cell. The zygote divides and develops into an embryo.
The ovary is the female reproductive organ of a flowering plant. It is located in the flower and contains the ovules. The ovary develops into a fruit after fertilization.