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: Psychiatry
Features of delirium: 
Select and explain. 
A. Deficit of attention (Attention Deficit), B. Autonomic instability (dysfunction), C. Altered sleep wake pattern, D. All
D: All
Answer: D: All 
Explanation: A. i.e. Deficit of attention; B. i.e. Autonomic instability; C. i.e. Altered sleep wake pattern