The correct option is D Methaemoglobinaemia
Blue baby syndrome is a condition characterized by the bluish discoloration of the skin seen in newborns. This syndrome is usually caused by methemoglobinemia which is the presence of a higher than normal level of methemoglobin rather than ferrous haemoglobin in the blood. Methemoglobin is a form of haemoglobin that contains ferric [Fe3+] iron and has a decreased ability to bind oxygen.