In diploid organisms, which of the following undergoes meiosis?

The correct answer is Option (2) → Sporogenous tissue

Meiosis halves the chromosome number. In a diploid plant, it takes place only in diploid cells that are to form spores. The haploid cells of the male and female gametophytes divide, if at all, by mitosis.

Option (1) Vegetative cell — Incorrect. The vegetative cell is the bigger of the two cells of a pollen grain. It is haploid and has food reserves. It does not undergo meiosis.

Option (2) Sporogenous tissue — Correct. Its cells are diploid. Each one is a microspore mother cell, and by meiosis it forms a tetrad of four haploid microspores.

Option (3) Pollen grain — Incorrect. A pollen grain is the microspore itself, already haploid. It divides by mitosis to form the vegetative cell and the generative cell.

Option (4) Synergids — Incorrect. The two synergids sit at the micropylar end of the embryo sac, beside the egg cell. They are haploid cells of the female gametophyte and do not undergo meiosis.

NCERT Extract:
Stamen, Microsporangium and Pollen Grain – “… When the anther is young, a group of compactly arranged homogenous cells called the sporogenous tissue occupies the centre of each microsporangium. Microsporogenesis : As the anther develops, the cells of the sporogenous tissue undergo meiotic divisions to form microspore tetrads.”