Which of the following statements is correct for the pollen tube?

Through which cell of the embryo sac does the pollen tube enter the embryo sac?

The pollen tube usually enters the embryo sac through:

In . . . . . . pollen grains cause allergy.

Identify the correct sequence of events of pollen-pistil interaction given below.
$(a)$ Pollen tube grows through the stigma,style and reaches the ovule.
$(b)$ Pollen grain lands on the stigma.
$(c)$ Pollen germinates to form pollen tube.
$(d)$ Pollen tube carrying $2$ male gametes enters the ovule.
Choose the correct option.

If the pollen grain is compatible,the pistil accepts it and promotes which of the following events?