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: ENT
[{'content': 'All of the following are true about antrochonal polyp,except - \nSelect and explain. \nA. Single, B. Unilateral, C. Premalignant, D. Arises from medullary antrum', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Antrochoanal polyp is non-cancerous growth arising from the mucous membrane of the maxillary sinus and reaches the opening of the sinus in the nasal cavity.\nIt is single and unilateral, i.e. it occurs in one of the maxillary sinus.', 'role': 'assistant'}]