This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Introduction and gametogenesis., Subject name: Anatomy
During spermatogenesis, chromosome no. reduces to haploid at:- 
Select and explain. 
A. At mitosis, B. Meiosis -I, C. Meiosis-II, D. None of above
B: Meiosis -I
Answer: B: Meiosis -I 
Explanation: The first meiotic division is known as the reduction division in which each primary spermatocyte yields two secondary spermatoctyes. Each contains 23 (Haploid) chromosomes consist of two varieties 22+X and 22+Y. Here 22 are autosomes and X & Y are sex chromosomes.