Choose the odd one in each of the following :
(a) Sperm; implantation; fertilisation; ovum; afterbirth.
(b) Relaxin; cervix dilates; amniotic sac ruptures; child birth; follicle.
(a) Oestrogen; progestrone; testosterone; prolactin.
(b) Ovary; fallopian tube; ureter; uterus.
(c) Seminiferous tubule; ovum; epididymis; sperm duct; urethra.
(d) Sperm; implantation; fertilisation; ovum; after birth.