Which of the following haemoglobin (Hb) estimation will be diagnostically helpful in a case of beta thalassemia trait?

Patients with thalassemia minor or thalassemia trait have a modest anemia with hematocrit between 28% and 40%. The MCV ranges from 55 fL to 75 fL, and the red blood cell count is normal or increased. The reticulocyte count is normal or slightly elevated. The peripheral blood smear is mildly abnormal, with hypochromia, microcytosis, and target cells. In contrast to -thalassemia, basophilic stippling is present. Hemoglobin electrophoresis shows an elevation of hemoglobin A2 to 4-8% and occasional elevations of hemoglobin F to 1-5%. Ref: Linker C.A., Damon L.E., Damon L.E., Andreadis C. (2013). Chapter 13. Blood Disorders. In M.A. Papadakis, S.J. McPhee, M.W. Rabow (Eds), CURRENT Medical Diagnosis & Treatment 2013.