What is not required for seed formation in cleistogamous flowers?

The diagram given below depicts:

Characteristics of wind-pollinated pollen grains are that they are:

Which one of the following is not a correct explanation of cross-pollination?

Identify the set of correct statements:
$A$. The flowers of Vallisneria are colourful and produce nectar.
$B$. The flowers of water lily are not pollinated by water.
$C$. In most of water-pollinated species,the pollen grains are protected from wetting.
$D$. Pollen grains of some hydrophytes are long and ribbon like.
$E$. In some hydrophytes,the pollen grains are carried passively inside water.
Choose the correct answer from the options given below.

The process where pollen grains from a flower reach the stigma of a flower on a different plant is called: