On which chromosomes are the genes associated with $\alpha$-thalassemia and $\beta$-thalassemia respectively located?

• A
  $16^{\text{th}}$ and $11^{\text{th}}$
• B
  $11^{\text{th}}$ and $16^{\text{th}}$
• C
  $18^{\text{th}}$ and $11^{\text{th}}$
• D
  $12^{\text{th}}$ and $18^{\text{th}}$