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: Pharmacology
Propranolol should not be given to a patient on treatment with which of the following drug ? 
Select and explain. 
A. Nifedipine, B. Nitrates, C. ACE inhibitors, D. Verapamil
D: Verapamil
Answer: D: Verapamil 
Explanation: None