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: Physiology
[{'content': 'Contraceptive action of combined pill is mainly due to: \nSelect and explain. \nA. Decrease in tubal motility, B. Prevents the fertilization, C. Prevents the implantation of fertilized egg, D. Inhibits ovulation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]