<prompt> The concentration of methemoglobin to cause cyanosis-5 gmdl2 gmdl1.5 gmdl12 gmdl  <response>: For Cyanosis to occur,Sulfhemoglobin should be equal or more than 0.5gmdLMethemoglobin should be equal or more than 1.5gmdLDeoxygenated hemoglobin should be equal or more than 5gmdL 