This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of Middle Ear (Otitis Media), Subject name: ENT
[{'content': 'Essential radiological feature of acute mastoiditis is: \nSelect and explain. \nA. Temporal bone pneumatization, B. Clouding of air cells of mastoid, C. Rarefaction of petrous bone, D. Thickening of temporal bone', 'role': 'user'}, {'content': 'Answer: B \nExplanation: (b) Clouding of air cells of mastoid(Ref. Cummings, 6th ed., 2161)X-ray mastoid and CT scan shows clouding of air cells because of the collection of exudates in them. Later on mastoid pneumatisation is lost and a single mastoid cavity may be seen.', 'role': 'assistant'}]