Human males continuously produce sperm and remain fertile throughout their lives; this ability is most likely the result of

A)large quantities of immature sperm cells produced and stored in the testes early in life that gradually mature.
B)a hormonally based signal transduction pathway that converts testicular tissue into iPSCs.
C)the activity of multipotent stem cells in the testes.
D)the conversion of surplus cell types, like red blood cells, into sperm.