α-thalassemia is controlled by two genes located on -

The correct answer is Option (4) → Chromosome 16

Thalassemia is a blood disorder in which too few globin chains are made. It is α-thalassemia when the α chain is affected. In β-thalassemia a single gene, HBB on chromosome 11, is affected.

NCERT Extract:
Mendelian Disorders – “… In α Thalassemia, production of α globin chain is affected while in β Thalassemia, production of β globin chain is affected. α Thalassemia is controlled by two closely linked genes HBA1 and HBA2 on chromosome 16 of each parent and it is observed due to mutation or deletion of one or more of the four genes.”