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: Medicine
Subdural effusions in association with acute bacterial meningitis are: 
Select and explain. 
A. The result of inadequate treatment, B. Indicative of a bleeding disorder, C. Usually fatal, D. A common occurrence
D: A common occurrence
Answer: D: A common occurrence 
Explanation: Subdural effusions are a common complication of acute bacterial meningitis, occurring in 30-50% of cases. The exact pathogenesis is unknown, but the effusions are more frequent in young infants, usually sterile, and not related either to inadequate therapy or to a bleeding disorder. They are frequently asymptomatic and rarely fatal. Ref: Ropper A.H., Samuels M.A. (2009). Chapter 32. Infections of the Nervous System (Bacterial, Fungal, Spirochetal, Parasitic) and Sarcoidosis. In A.H. Ropper, M.A. Samuels (Eds), Adams and Victor's Principles of Neurology, 9e.