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
False perception without external stimulus is: 
Select and explain. 
A. Illusion, B. Hallucination, C. Delirium, D. Delusion
B: Hallucination
Answer: B: Hallucination 
Explanation: Hallucination