What is the function of the polar nuclei?

To fuse with the male gamete and form the endosperm

The correct answer is Option (3) → To fuse with the male gamete and form the endosperm.

Explanation:

• The polar nuclei are located in the central cell of the embryo sac.
• During double fertilization in angiosperms, one male gamete fuses with the egg cell to form the zygote (2n), which develops into the embryo.
• The other male gamete fuses with the two polar nuclei to form the triploid (3n) primary endosperm nucleus (PEN).
• The endosperm later develops into a nutritive tissue that provides food to the developing embryo.

Other options :

To assist in pollen tube guidance – Incorrect, because synergids, not polar nuclei, help guide the pollen tube.

To develop into the embryo – Incorrect, because the zygote (not the polar nuclei) develops into the embryo.

To protect the ovule – Incorrect, because integuments and other ovular structures provide protection, not the polar nuclei.

Final Answer: To fuse with the male gamete and form the endosperm.