This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hematology, Subject name: Pediatrics
[{'content': "Ba&;s hydrops fetalis is lethal because \nSelect and explain. \nA. Hb Ba's cannot bind oxygen, B. The excess a - globin form insoluble precipitates, C. Hb Ba's cannot release oxygen to fetal tissues, D. Microcytic red cells become trapped in the placental", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ba hydrops fetalis is a lethal complication of alpha thalassemia trait where oxygen can&;t release from hemoglobin. Hb Bas is formed of 4 gamma chains. The oxygen affinity is so high that it releases very little oxygen into the fetal tissues. Reference: Ghai essential of pediatrics, eighth edition, p.no:342', 'role': 'assistant'}]