Which of the following describes an example of fertilization in higher organisms

Step 1: Analyze the question The question asks which option describes fertilization. Fertilization is a specific event, and it is not the same as mating, pollination or ejaculation.

Step 2: The concept Fertilization is the fusion of a male gamete (sperm or male nucleus) with a female gamete (egg or ovum). It produces a diploid zygote. In animals this happens in the oviduct (fallopian tube). In flowering plants it happens in the ovule, after the pollen tube delivers the male nucleus.

Step 3: Check each option

• A. Fusion of sperm and egg nuclei. This matches the definition exactly. The haploid (n) nuclei fuse to give a diploid (2n) zygote, so it is correct.
• B. Pollen grain landing on a sticky stigma. This is pollination, the transfer of pollen to the stigma. It comes before fertilization but is not fertilization.
• C. Ejaculation of the egg and pollen grain. This is wrong. Eggs and pollen grains are not ejaculated, and the statement mixes up animal and plant terms.
• D. Ejaculation of sperm into the female body. This is insemination (copulation or semen deposition). Sperm still has to travel and fuse with the egg, and that fusion is the fertilization.

Step 4: Answer The correct option is A.

Step 5: Exam tip Remember the order of events: Pollination or insemination comes first, and fertilization (gamete fusion) comes after. If an option describes only the transfer or arrival of gametes, it is not fertilization. Look for words like "fusion" or "union" of gametes or nuclei.