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
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: 
Select and explain. 
A. Phenytoin, B. Propranolol, C. Methylphenidate, D. Trihexyphenedyl
B: Propranolol
Answer: B: Propranolol 
Explanation: B i.e. Propranolol