Progestin-estradiol combined contraceptive pills inhibit ovulation by
A. negative feedback on the release of estrogen from ovary required for follicular development in follicular phase
B. Preventing the uterine physiological and morphological changes required for implantation
C. inhibiting the secretion of follicle stimulating hormone (FSH) and lateinising hormone (LH) that are necessary for ovulation
D. both (a) and (c)
