Choose the odd one in each of the following :
(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.
(a) Testosterone
(b) Ureter
(c) Ovum
(d) Sperm