Which one of the following structure is haploid (n) in relation to ma…

The correct answer is Option (1) → Secondary spermatocytes

In spermatogenesis, diploid spermatogonia (46 chromosomes) grow into primary spermatocytes. The first meiotic division is the reduction division: each primary spermatocyte gives two haploid secondary spermatocytes with 23 chromosomes each. These go on to form spermatids and then sperms, all haploid.

Option (1) Secondary spermatocytes — Correct. Spermatogonia and primary spermatocytes are diploid. The primary spermatocyte divides by meiosis I to give two secondary spermatocytes, which are haploid (23 chromosomes).

Option (2) Primary spermatocytes — Incorrect. They are diploid (46 chromosomes); meiosis has not yet started in them.

Option (3) Leydig cells — Incorrect. These are body cells between the seminiferous tubules that secrete androgens. They are diploid.

Option (4) Sertoli cells — Incorrect. Sertoli cells nourish the developing germ cells. They are diploid body cells, not gametes.

NCERT Extract:
Gametogenesis – “The primary sex organs – the testis in the males and the ovaries in the females – produce gametes, i.e, sperms and ovum, respectively, by the process called gametogenesis. In testis, the immature male germ cells (spermatogonia) produce sperms by spermatogenesis that begins at puberty. The spermatogonia (sing. spermatogonium) present on the inside wall of seminiferous tubules multiply by mitotic division and increase in numbers. Each spermatogonium is diploid and contains 46 chromosomes. Some of the spermatogonia called primary spermatocytes periodically undergo meiosis. A primary spermatocyte completes the first meiotic division (reduction division) leading to formation of two equal, haploid cells called secondary spermatocytes, which have only 23 chromosomes each.”