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: Physiology
True regarding HbA2 is/are? 
Select and explain. 
A. It has more capacity to carry oxygen, B. Concentration is more than HbA, C. Level is increased in Thalasemia, D. Consists of 2 alpha and 2 beta chains
B: Concentration is more than HbA
Answer: B: Concentration is more than HbA 
Explanation: Ans. is'c'i.e., Level is increased in ThalassemiaRef: Ganong 23d/e p. 523-525 https: / /www. aafp.org/ alp / 2009 /08 1 5 /p3 39.html"The hemoglobin electrophoresis with beta thalassemia trait usually has reduced or absent HbA, elevated levels of HbA2. and increased HbF.However, a normal concentration of HbA2 does not rule out beta thalassemia trait. especially if there was coexistent iron deficiency, which can lower HbA2 levels into the normal range.""Hemoglobin A2 may be increased in beta thalassemia or in people who are heterozygous for the beta thalassemia gene.