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
Which of the following drugs causes constipation ? 
Select and explain. 
A. Propranolol, B. Verapamil, C. Nitroglycerin, D. Captopril
B: Verapamil
Answer: B: Verapamil 
Explanation: None