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
Ba&;s hydrops fetalis is lethal because 
Select and explain. 
A. 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
C: Hb Ba's cannot release oxygen to fetal tissues
Answer: C: Hb Ba's cannot release oxygen to fetal tissues 
Explanation: 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