The function of zona pellucida layer is to:

The correct answer is Option (2) → Block the entry of additional sperms

The zona pellucida is the layer that surrounds the ovum. It is the first barrier that a sperm meets at fertilisation.

(1) Induce mitotic division — Incorrect. The zona pellucida does not start any division. The zygote divides by mitosis later, as it passes down the fallopian tube.

(2) Block the entry of additional sperms — Correct. When one sperm touches the zona pellucida, it induces changes that block the entry of additional sperms. This makes sure that only one sperm fertilises the ovum.

(3) Allow the entry of multiple sperms — Incorrect. This is the opposite of what happens. The entry of many sperms would upset the number of chromosomes.

(4) Provide nutrition to sperm during fertilization — Incorrect. The sperm gets no nutrition from this layer. The secretions of the acrosome help it to pass through the layer.

NCERT Extract:
Fertilisation and Implantation – …

Figure 2.10 Ovum surrounded by few sperms