How many polar nuclei migrate to the centre of the developing female gametophyte from each pole of the female gametophyte?

Which of the following is the first cell of the female gametophytic generation in angiosperms?

The following figure shows a diagrammatic view of a typical anatropous ovule. What are $P$,$Q$,and $R$?

What is the arrangement of nuclei in a typical angiosperm embryo sac?

In angiosperms,the functional megaspore of a linear tetrad is the:

Given below are two statements: One is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A):$ $A$ typical unfertilised,angiosperm embryo sac at maturity is $8$-nucleate and $7$-celled.
Reason $(R):$ The egg apparatus has $2$ polar nuclei.
In the light of the above statements,choose the correct answer from the options given below: