Sickle cell anaemia is due to : -

Question

( A ) Change of Amino acid either $\alpha$ or $\beta$ chain of Haemoglobin
( B ) Change of Amino Acid in $\beta$-chain of Haemoglobin
( C ) Change of Amino Acid in $\alpha$-chain of Haemoglobin
( D ) Change of Amino acid in both $\alpha$ and $\beta$ chain of Haemoglobin