This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
Drug contra-Indicated in bilateral renal aery stenosis 
Select and explain. 
A. Propanolol, B. Guanethidine, C. Captopril, D. Amlodipine
C: Captopril
Answer: C: Captopril 
Explanation: ACE inhibitors are contraindicated in patients with renal aery stenosis as they can cause renal failure in them. Especially in bilaterl renal aery stenosis Unilateral renal aery stenosis- ACI in usage depends on clinical correlation All the other drugs are safe in renal aery stenosis. Ref: KD tripathi 8th ed. Page no 130