Which among the following statement is correct about fertilization ?

Fusion of sperm with egg nuclei

The correct answer is Option (3) – Fusion of sperm with egg nuclei

Fertilization is the process by which a sperm cell (spermatozoon) combines with an egg cell (ovum) to form a new organism. During fertilization, the sperm cell penetrates the egg cell's protective layer and fuses with the egg nucleus, combining their genetic material. This fusion of genetic material from both parents initiates the development of a new individual.

The other options are incorrect:

1. Mixing of semen with vaginal fluid: This describes the process of ejaculation, where semen (which contains sperm) is released into the female's reproductive tract. However, fertilization occurs when a sperm cell fuses with an egg cell, not when semen mixes with vaginal fluid.
2. Release of sperm from testis: Sperm cells are indeed released from the testes during ejaculation, but this is not the process of fertilization itself. Fertilization occurs when a sperm cell successfully fuses with an egg cell.
3. Release of egg from the ovary: The release of an egg from the ovary is known as ovulation. It is a prerequisite for fertilization because it makes the egg available for fertilization in the fallopian tube. However, fertilization itself involves the fusion of sperm with the egg nucleus, not just the release of the egg from the ovary.