In plants one male gamete fuses with the egg to form a diploid zygote; the other fuses with the polar nuclei to form the triploid endosperm.

• A. Fertilisation
• B. Meiosis
• C. Mitosis
• D. Double fertilisation

Answer: (D)

Double fertilisation is being described. In flowering plants, the pollen tube delivers two sperm cells. One sperm fuses with the egg to form a diploid zygote, which will develop into the embryo. The other sperm fuses with the two polar nuclei in the central cell to form a triploid endosperm, which nourishes the developing embryo. This combination of two fertilisation events is unique to angiosperms and is what the question is detailing. The other terms don’t fit because meiosis is the cell division that makes haploid gametes, and mitosis is growth division after fertilisation; fertilisation alone doesn’t capture the two simultaneous fertilisation events.