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': 'That pa of mind which is working on reality principle is: \nSelect and explain. \nA. ID, B. Ego, C. Super ego, D. Super ego', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B. i.e. Ego', 'role': 'assistant'}]