Which of the following statements are true?
$I$. Species diversity provides stability to the ecosystem.
$II$. Communities with more species tend to be more stable than those with fewer species.
$III$. Ecosystems with higher biodiversity are more productive than ecosystems with lower biodiversity.
$IV$. Biodiversity is not essential for the maintenance and health of the ecosystem.
Choose the correct option.

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