This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'The progestogenic emergency contraceptive pills act by - \nSelect and explain. \nA. Altered cervical secretion, B. Inhibition of ovulation, C. Anti-implantation effect, D. Inhibition of LH secretion', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Anti-implantation effect o If ovulation and feilization occur, the blastocyte fails to implant (anti-implantation effect) because endometrium is either hyperproliferativer or hypersecretory; not suitable for nidation. o This is the mechanism of action of postcoital (emergency) contraceptive pills.", 'role': 'assistant'}]