Which one among the following is the correct order the strength of acids?

• Correct answer
  A

  $\mathrm{H}_2 \mathrm{SO}_4 \gt \mathrm{H}_3 \mathrm{PO}_3 \gt \mathrm{CH}_3 \mathrm{COOH}$
• B

  $\mathrm{H}_2 \mathrm{PO}_3 \gt \mathrm{H}_2 \mathrm{SO}_4 \gt \mathrm{CH}_3 \mathrm{COOH}$
• C

  $\mathrm{CH}_3 \mathrm{COOH} \gt \mathrm{H}_3 \mathrm{PO}_3 \gt \mathrm{H}_2 \mathrm{SO}_4$
• D

  $\mathrm{CH}_3 \mathrm{COOH} \gt \mathrm{H}_2 \mathrm{SO}_4 \gt \mathrm{H}_3 \mathrm{PO}_3$

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