Consider the following statements:
$I.$ Algal blooms are formed by free-floating algae.
$II.$ Algal blooms cause fish mortality and deterioration of water quality.
$III.$ Water hyacinth, the world's most problematic aquatic weed, is also called 'Terror of Bengal'.
Which of the statements given above are correct about algal blooms?

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