The pair of gases responsible for acid rain are

• A

  $\mathrm{H}_2, \mathrm{O}_3$
• B

  $\mathrm{CH}_4, \mathrm{O}_3$
• Correct answer
  C

  $\mathrm{NO}_2, \mathrm{SO}_2$
• D

  $\mathrm{CO}, \mathrm{CH}_4$

Solution

Oxides of nitrogen and sulphur are responsible for acid rain.
Due to the presence of $\mathrm{HNO}_3$ and $\mathrm{H}_2 \mathrm{SO}_4$ (strong acids) rain water becomes acidic and rain is called the acid rain.

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