The wall of the pollen tube is made up of:

What do '$c$' and '$d$' represent in the given figure?

In over $60\%$ of angiosperms,pollen grains are shed at the $2$-celled stage. In less than $40\%$ of angiosperms,pollen grains are shed at the $3$-celled stage.

Even after killing the generative cell with a laser beam,the pollen grain of a flowering plant germinates and produces a normal pollen tube because:

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:

The mature male gametophyte in angiosperms is typically composed of how many cells?