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
Nihilistic ideas are seen in - 
Select and explain. 
A. Depression, B. Schizophrenia, C. Mania, D. OCN
A: Depression
Answer: A: Depression 
Explanation: Delusions of nihilism (nihilistic ideas) are characteristic of major depression.