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: Social & Preventive Medicine
[{'content': 'Mestranol acts as contraceptic by \nSelect and explain. \nA. Inhibiting FSH secretion, B. Inhibiting tubal motility, C. Inhibiting ascent of sperm, D. Inhibiting Implantation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]