Which is an incorrect statement?
$I$. Each cell of sporogenous tissue in anther is capable of giving rise to a microspore tetrad.
$II$. The pollen grain represents the male gametophyte.
$III$. Pollen grains are usually triangular and $10-15 \mu m$ in diameter.
$IV$. Sporopollenin is one of the most resistant organic materials,which can be destroyed only by strong acids and alkalis.

• A
  $I, II$ are incorrect but $III, IV$ are correct
• B
  $III, IV$ are incorrect but $I, II$ are correct
• C
  $I, III$ are incorrect but $II, IV$ are correct
• D
  $II, IV$ are correct but $I, III$ are incorrect