This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and PNS, Subject name: ENT
[{'content': 'Rhinolith can cause perforation of nasal septum by- \nSelect and explain. \nA. Pressure necrosis, B. Malignant transformation, C. Autoimmune reaction, D. Hypersensitivity reaction', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Pressure necrosis * A rhinolith usually forms around the nucleus of a small exogenous foreign body, blood clot or inspissated secretions by slow deposition of calcium and magnesium salts.* Over a period of time, it grows into a large, irregular mass, which fills the nasal cavity and then may cause pressure necrosis of the septum and/or lateral wall of nose.", 'role': 'assistant'}]