<prompt> Which of the following Anti-retro viral agent can cause bone marrow suppression?RitonavirZidovudineStavudineDidanosine  <response>: ZIDOVUDINE: Is a NI NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR against HIV-1, HIV-2 and HTLVs I and II. It causes Competitive inhibition but no impact on cells already infected with HIV . It causes Bone Marrow Suppression, Lipodystrophy, Erythrocytic Macrocytosis, Skeletal muscle myopathy, Hepatic toxicity and on chronic use can cause Nail hyperpigmentation 