Identify the correct statements from the following I. Photochemical smog has high concentration of oxidising agents II. $\quad \mathrm{NO}_2$ is present in classical smog III. Higher concentration of $\mathrm{SO}_2$ in air can cause stiffness of flower buds IV. pH of rain water is approximately 7.5

• Correct answer
  A

  I & III
• B

  I & II
• C

  III & IV
• D

  II & III

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