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
Thiazide diuretic used when GFR<30 ml/min? 
Select and explain. 
A. Metolazone, B. Benzthiazidc, C. Chlohiazide, D. Hydrofulthiazide
A: Metolazone
Answer: A: Metolazone 
Explanation: Ans. is 'a' i.e., Metolazone o Metolazone is the only thiazide which is effective in severe renal failure.