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: Pathology
Both beta chains of haemoglobin are abnormal in 
Select and explain. 
A. Heterozygous sickle cell trait, B. Thalassemia major, C. Homozygous sickle cell anemia, D. Megaloblastic anemia
B: Thalassemia major
Answer: B: Thalassemia major 
Explanation: None