Read the passage and answer the following questions:
A typical microsporangium, when observed in a transverse section, has a nearly circular shape. It is typically surrounded by four layers of walls: the epidermis, endothecium, middle layers, and the tapetum. The outer three wall layers serve to protect the microsporangium and aid in the anther's opening to release the pollen. The innermost wall layer, known as the tapetum, provides nourishment to the developing pollen grains. Tapetum cells are characterized by their dense cytoplasm and often contain multiple nuclei. In angiosperms, an anther usually consists of two lobes, each with two theca, making it dithecous. The theca are often separated by a longitudinal groove. The anther itself has a tetragonal shape with four microsporangia situated at its corners, two in each lobe. These microsporangia undergo further development and transform into pollen sacs.

What does a pollen grain represents ?

Male gametophyte.

The correct answer is Option (3) -Male gametophyte.

A pollen grain represents the male gametophyte of a flowering plant. The male gametophyte is  haploid (having one set of chromosomes) that develops from a microspore. The microspore is produced in the anther of the stamen.

The pollen grain contains two cells: the vegetative cell and the generative cell. The vegetative cell produces the pollen tube, which is a long, thin structure that helps the pollen grain to reach the ovule. The generative cell divides to form two sperm cells.

When the pollen grain lands on the stigma of a flower, the pollen tube grows down through the style and into the ovary. The sperm cells are released from the pollen tube and fertilize the egg cell in the ovule. This fertilization event results in the formation of a seed.

Therefore, the answer is male gametophyte.