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': '"Thumb sign" in laterral X - ray neck seen in \nSelect and explain. \nA. Epiglottitis, B. Internal hemouhage, C. Carcinoma epiglottis, D. Saccular cyst', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]