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
[{'content': 'Delusion of Nihilism and Early morning insomnia are characteristic features of \nSelect and explain. \nA. Mania, B. Major depression, C. Personality disorder, D. Personality disorder', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Major depression', 'role': 'assistant'}]