Some Women Prolong Breastfeeding or Lactation in General as a Form

Some women prolong breastfeeding or lactation in general as a form of birth control. How would extension of lactation be effective in preventing pregnancy?

A) Lactation stimulates production of placental lactinogen, which is a pregnancy hormone and prevents the corpus luteum from degrading and advancing the reproductive cycle.
B) Prolactin is the hormone that corresponds with lactation. It also inhibits ovulation at the pituitary gland level, so as long as lactation is actively occurring, ovulation is prevented.
C) Breastfeeding stimulates production of oxytocin, which causes the endometrium to slough off and exit the body in a menstrual period, preventing implantation of a zygote.
D) The physical stimulation of breastfeeding causes high levels of progesterone to be produced, which cause secretions in the reproductive tract that are hostile to sperm.