Which of the following prevents pollen germination or pollen tube growth?

Which one of the following usually does $NOT$ promote self-pollination?

Match the following contrivances from Column-$I$ with their examples in Column-$II$.

Column-$I$	Column-$II$
$i$. Protandry	$a$. Calotropis
$ii$. Prepotency	$b$. Tobacco
$iii$. Self sterility	$c$. Sunflower
$iv$. Herkogamy	$d$. Apple

What is self-incompatibility? Why does self-pollination not lead to seed formation in self-incompatible species?

What is the outbreeding device,where the stamens and carpels mature at different times called?

Which of the following devices promote cross-pollination?
$(i)$ Non-synchronization of pollen release and stigma receptivity
$(ii)$ Anther and stigma are placed at different positions
$(iii)$ Monoecious plants
$(iv)$ Production of dioecious plants
$(v)$ Self-incompatibility
$(vi)$ Anther and stigma are placed close to each other
$(vii)$ Self-compatibility