This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: RH Incompatibility, Subject name: Gynaecology & Obstetrics
[{'content': 'Most severely affected child in Rh-isoimmunization patients if: \nSelect and explain. \nA. Rh negative mother with Rh positive in 2nd child, B. Rh positive mother with Rh negative in 2nd child, C. Rh positive mother with Rh negative in 1st child, D. Rh negative mother with Rh negative in 2nd child', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Rh negative mother delivering Rh positive child for the first time gets sensitized to the D antigen of the fetus and stas developing D antibody which is fully loaded in maternal circulation. When Rh negative mother delivers her Rh positive 2nd child the antibody in the fetal circulation causes hemolysis in fetal circulation and the child is most severely affected.', 'role': 'assistant'}]