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
Essential radiological feature of acute mastoiditis is - 
Select and explain. 
A. Temporal bone pneumatisation, B. Clouding of air cells of mastoid, C. Rarefaction of petrous, D. Thickening of temporal bone
B: Clouding of air cells of mastoid
Answer: B: Clouding of air cells of mastoid 
Explanation: None