This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
Bart's hydrops fetalis is lethal because 
Select and explain. 
A. Hb Bart's cannot bind oxygen, B. Hb Bart's cannot release oxygen to fetal tissues, C. Microcytic red cells become trapped in the placental, D. The excess a - globin form insoluble precipitates
B: Hb Bart's cannot release oxygen to fetal tissues
Answer: B: Hb Bart's cannot release oxygen to fetal tissues 
Explanation: Bart hydrops fetalis is a lethal complication of alpha thalassemia trait where oxygen can't release from hemoglobin