Which of the following is an enzyme-resistant substance?

Given below are two statements: One is labelled as Assertion $(A)$ and the other is labelled as Reason $(R).$
Assertion $(A) :$ Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus.
Reason $(R):$ Presence of more than one nucleus in the tapetum increases the efficiency of nourishing the developing microspore mother cells.
In light of the above statements,choose the most appropriate answer from the options given below:

Pollen grains are generally . . . . . . in outline measuring . . . . . . micrometers in diameter.

$A$ typical angiosperm anther is . . . . . . and . . . . . . .

Pollen grains are well preserved as fossils because of the presence of . . . . . . .

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: