In anther culture,some diploid plants were reported along with haploids. They have evolved from:

In plant $A$,$2n = 12$ and in plant $B$,$2n = 16$. Then the ploidy number (total chromosome number) of the hybrid plant resulting from cross-breeding is:

Dioecious plant $- P$
Monoecious plant $- Q$
Select the correct option for $P$ and $Q$.
$\quad\quad\quad P\quad\quad Q$

Select the option that represents the correct statement.

What is the nature of male gametes in angiosperms?

Identify the plant parts that consist of two generations,one within the other:
$(a)$ Pollen grains inside the anther
$(b)$ Germinated pollen grain with two male gametes
$(c)$ Seed inside the fruit
$(d)$ Embryo sac inside the ovule