How many microsporangia are located at the corners of a typical bilobed anther of angiosperm?

$A$ microsporophyll bears $.....$.

List the products derived from pollen grains and explain their uses.

Pollen grain develops from . . . . . . of anther.

$A$ - Only some cells of the sporogenous tissue are capable of giving rise to microspore tetrad.
$R$ - The microspores are arranged in a cluster of four cells - the microspore tetrad.

Choose the correct option for $PMC$. (in $n$)