Microspore tetrads are formed due to meiotic division occurring in......

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 number of pollen sacs in a dithecous anther is

During an excavation of soil,pollen fossils were retrieved from the deepest layer of soil. The pollen grains remained as fossils because

Male gametes in angiosperms are formed by the division 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.