This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Contraceptives, Subject name: Gynaecology & Obstetrics
All of the following mechanisms of action of Oral contraceptive pill are true, except: 
Select and explain. 
A. Inhibition of ovulation, B. Prevention of feilization, C. Interference with implantation of feilized ovum, D. Interference with placental functioning
D: Interference with placental functioning
Answer: D: Interference with placental functioning 
Explanation: Mechanisms of action of oral contraceptive pill Suppresses pituitary hormones, FSH and LH peak and through their suppression prevents ovulation. Progestogen causes atrophic changes in the endometrium and prevents nidation. Progestogen also acts on the cervical mucus making it thick and tenacious and impenetrable by sperms. Increases the tubal motility, so the feilized egg reaches the uterine cavity before the endometrium is receptive for implantation.