Which of the following pairs of oxoacids have basicity as $2 ?$

• Correct answer
  A

  $\mathrm{H}_3 \mathrm{PO}_3, \mathrm{H}_2 \mathrm{SO}_4$
• B

  $\mathrm{H}_3 \mathrm{PO}_2, \mathrm{H}_2 \mathrm{SO}_3$
• C

  $\mathrm{H}_3 \mathrm{PO}_4, \mathrm{H}_3 \mathrm{PO}_2$
• D

  $\mathrm{H}_2 \mathrm{~S}_2 \mathrm{O}_8, \mathrm{H}_3 \mathrm{PO}_2$

Hence, the correct answer is option: 'A'.