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
Which of the following feature is not common between delirium and dementia? 
Select and explain. 
A. Disturbance of memory, B. Hallucinations, C. Delusions, D. Fluctuating course
D: Fluctuating course
Answer: D: Fluctuating course 
Explanation: Delirium is characterized by acute onset and fluctuating course,  where as dementia patients with chronic and downhill course.