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: Anaesthesia
Bone marrow depression is seen with chronic administration of ? 
Select and explain. 
A. Isoflurane, B. N20, C. Ether, D. Halothane
B: N20
Answer: B: N20 
Explanation: Ans. is 'b' i.e., N20