What do plants develop various devices to promote?

$A$ dioecious flowering plant prevents both

Continuous self-pollination in a species leads to:

Explain what are outbreeding devices. Give its importance.

Self-incompatibility is a device for
$I$. Ensuring cross-pollination
$II$. Preventing self-pollination
$III$. Ensuring self-fertilisation
$IV$. Genetic control for self-fertilisation
Choose the correct statements from those given above.

What is self-incompatibility?