Erythroblastosis fetalis is a severe condition caused by the incompatibility of blood groups between the mother and fetus, specifically involving the: MCQ with Answer and Explanation

Erythroblastosis fetalis (hemolytic disease of the newborn) is primarily caused by Rh incompatibility. It occurs when an Rh-negative mother carries an Rh-positive fetus. During the first pregnancy, fetal Rh+ red blood cells may enter the mother's circulation, prompting her to produce anti-Rh antibodies. In subsequent pregnancies with an Rh+ fetus, these antibodies cross the placenta and destroy the fetal red blood cells, causing severe anemia and jaundice.