Which of the following division turn secondary spermatocytes into four equal, haploid spermatids ?

Second meiotic divison.

The correct answer is Option (3)- Second meiotic division.

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.

The secondary spermatocytes undergo the second meiotic division to produce four equal, haploid spermatids.