Which of the following mechanisms prevents self-pollination?

This is a genetic mechanism that prevents self-pollination by inhibiting pollen germination or pollen tube growth in the pistil,thereby preventing fertilization.

Cross-fertilisation is favoured by

Given below are two statements.
Statement $I$: Self-incompatibility is a device that prevents outbreeding.
Statement $II$: Self-incompatibility is a genetic mechanism due to which germination of pollen on the stigma of the same flower is inhibited.
In the light of the above two statements,choose the correct answer from the options given below.

$A$ dioecious flowering plant prevents both

Does self-incompatibility impose any restrictions on autogamy? Give reasons and suggest the method of pollination in such plants.