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
Simple mastoidectomy is done for - 
Select and explain. 
A. Lateral sinus thrombophlebitis, B. Small localized cholesteatoma, C. ASOM, D. Acute mastoiditis
D: Acute mastoiditis
Answer: D: Acute mastoiditis 
Explanation: None