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 one of the following drugs causes constipation? 
Select and explain. 
A. Propranolol, B. Verapamil, C. Nitroglycerin, D. Captopril
B: Verapamil
Answer: B: Verapamil 
Explanation: Ans. is 'b' i.e., Verapamil Drugs causing constipation : Aluminium Hydroxide Ion exchange resins Verapamil Calcium carbonate Barium sulphate Opiates Ferrous sulphate Ganglionic blockers Phenothiazines Tricyclic antidepresants