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': 'Cawheel sign is seen in \nSelect and explain. \nA. ASOM, B. CSOM, C. Serous otitis media, D. Tuberculous otitis media', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Cawheel appearance is seen in ASOM. Leash of blood vessels appears along the handle of malleus and at the periphery of tympanic membrane impaing it a ca-wheel appearance. Later, whole of tympanic membrane including pars flaccida becomes uniformly red. Seen in stage of Presuppuration Reference: Dhingra; Chapter 10; Page no: 62', 'role': 'assistant'}]