This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
[{'content': 'Most common site for initiation of stapedial otosclerosis is: \nSelect and explain. \nA. Fissula ante-fenestram, B. Fossula post-fenestram, C. Footplate of stapes, D. Margins of stapes', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Most common site for otosclerosis to start is fissula ante-fenestram - an area lying in front of oval window. Other sites listed in the question are also affected but their involvement is less frequent.', 'role': 'assistant'}]