In vertebrate animals, spermatogenesis and oogenesis differ, in that:
A) oogenesis begins at the onset of sexual maturity.
B) oogenesis produces four haploid cells, whereas spermatogenesis produces only one functional spermatozoon.
C) oogenesis produces one functional ovum, whereas spermatogenesis produces four functional spermatozoa.
D) spermatogenesis begins before birth.
E) spermatogenesis is not complete until fertilization occurs.
