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: Pathology
[{'content': 'Trismus is  not seen: \nSelect and explain. \nA. Scleroderma., B. OSMF., C. Pemphigus., D. None.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Scleroderma:\xa0\nDifficulty in mouth opening due to involvement of perioral\xa0skin.', 'role': 'assistant'}]