In a young anther,the four rows of cells which later produce pollen are called:

Which cells are present in a $3$-celled pollen grain?

In flowering plants,a mature 'male gametophyte' is derived from a 'pollen mother cell' by

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:

Microsporangia develops into

Tapetal cells are characterized by