In which of the following transition meiosis occurs: (A) Primary to secondary spermatocyte, (B) Second spermatocyte to globular spermatid, (C) Germ cells to spermatogonium, (D) Spermatogonium to primary spermatocyte
Answer is A. Transition meiosis

Transition from mitosis to meiosis
The spermatogonia undergo mitosis to form the primary  spermatocytes, which then enter first meiotic division. They rest for 22 days and then rapidly complete the first meiotic division to form secondary spermatocytes.
During second meiotic division secondary spermatocyte divides into spermatids.