Which of the following anaesthetic agent causes bone marrow supression?

Nitrous oxide may cause bone marrow supression by interfering with the production of factors necessary for DNA synthesis. Nitrous oxide has few adverse effects, it is a mild cardiac depressant and pulmonary vasoconstrictor and is relatively contraindicated in patients with pulmonary hypeension. It cause diffusional hypoxia. It inhibits folate metabolism and is contraindicated in pregnancy. It promote expansion of internal gas-filled structures, and is avoided in patients with pneumothorax, pneumocephalus, and vascular air embolism.