Consider the following statements about eutrophication:
$I.$ Eutrophication is the natural ageing of a water body by nutrient enrichment.
$II.$ The accelerated ageing of lakes due to sewage and agricultural and industrial wastes is called cultural or accelerated eutrophication.
$III.$ The plant nutrients responsible for eutrophication are nitrates and phosphates.
$IV.$ Phosphates and nitrates accelerate the growth of algae which utilize oxygen and may deoxygenate the water enough to kill the fish and other aquatic animals.
Which of the statements given above are correct?

• A
  $I$ and $II$
• B
  $I, II$ and $III$
• C
  $I, III$ and $IV$
• D
  $I, II, III$ and $IV$