Spermatogonia are:
Correct option is B, Diploid stem cells. In Reproductive System, the accurate description is Diploid stem cells, and that is what you should commit to memory. Keep the definition tight and the role clear — Diploid stem cells is the option that correctly names the structure, process, or principle asked for in Reproductive System. Then Diploid stem cells is the answer you can defend. Check yourself by covering the options and writing the answer first, then matching the letter — that builds confidence. If the wording feels dense, translate it into everyday language first, then map that plain sentence back onto Diploid stem cells.
Ref: Animal physiology is Unit 7 of the CSIR NET Life Science Syllabus, covering core body systems. It accounts for roughly 10% of the total marks in Sections B and C.