Identify the correct statement among the following.

Arrange the following in the correct developmental sequence related to microsporogenesis:
$A$. Microspore tetrads
$B$. Sporogenous tissue
$C$. Pollen grains
$D$. Pollen mother cells
Choose the correct answer from the options given below:

The wall of the pollen tube is made up of:

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.

$60\; \%$ of the angiosperms shed their pollens at the

What is the approximate diameter of a pollen grain?