Thalassemia and sickle cell anaemia are caused by a problem in globin molicule synthesis .Select the correct statement
A. Both are due to a qualitative defect in globin chain synthesis
B. Both are due to a quantitative defect in globin chain synthesis
C. Thalassemeia is due to less synthesis of globin molecules
D. Sickle cell anaemia is due to a quantitative problem of globin molecules.