This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Microbiology
[{'content': 'Most common cause of cervical insufficiency is \nSelect and explain. \nA. Idiopathic, B. Previous dilatation, C. Exposure to DES, D. Conization', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The most common cause of cervical insufficiency is idiopathicCervical incompetence may be congenital due to the following:Mullerian anomaliesCollagen disordersExposure to DES or the causes may be acquiredObstetric trauma like cervical laceration during deliveryMechanical dilatationCervical Conization', 'role': 'assistant'}]