The correct option is B Puberty
Before puberty, the seminiferous tubules are in the form of cords. These seminiferous cords have cells of Sertoli surrounded by a basement membrane. The spermatogonia are present between Sertoli cells and basement membrane. At puberty, the seminiferous cords acquire central lumen and become seminiferous tubules and the spermatogonia starts dividing.
Thus, the correct answer is option (C), 'Puberty'.