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': 'A 25-year old man with a psychotic illness, was treated with haloperidol 30mg/day. On the third day he developed pacing, and inability to sit still at one place. The medication likely to be helpful is: \nSelect and explain. \nA. Phenytoin, B. Propranolol, C. Methylphenidate, D. Trihexyphenedyl', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Propranolol', 'role': 'assistant'}]