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: Gynaecology & Obstetrics
[{'content': "All of the following are features of progesterone pills except : \nSelect and explain. \nA. Acts by altering cervical mucous secretion, B. Break ovulation cycle, C. Failure rate is equal to that seen with OCP's, D. Irregular bleeding is a known complications", 'role': 'user'}, {'content': "Answer: C \nExplanation: Failure rate is equal to that seen with OCP's", 'role': 'assistant'}]