The graph given below represents the effect of sewage discharge on some important characteristics of river



Select the CORRECT option with respect to the peaks A and B.

• Correct answer
  A

  Peak A - Sharp increase in BOD, the disappearance of clean water organisms
  
  Peak B - Increase in dissolved oxygen, the reappearance of clean water organisms
• B

  Peak A - Increase in dissolved oxygen, the reappearance of clean water organisms
  
  Peak B - Sharp decline in dissolved oxygen, the disappearance of clean water organisms
• C

  Peak A - Sharp increase in BOD, the appearance of clean water organisms
  
  Peak B - Increase in dissolved oxygen, the disappearance of clean water organisms
• D

  Peak A - Increased number of anaerobic bacteria, the disappearance of clean water organisms
  
  Peak B - Sharp decline in dissolved ${\mathrm{O}}_2$, the reappearance of clean water organisms

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