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

Explain what are outbreeding devices. Give its importance.

Dichogamy,which helps in cross-pollination,is a floral mechanism in which:

The phenomenon in which anther and stigma grow and mature at the same time is called:

Match the following columns regarding plant breeding systems and select the correct option:
Column-$I$: $(i)$ Monoecious, (ii) Dioecious
Column-$II$: $(p)$ Prevents both autogamy and geitonogamy, $(q)$ Prevents autogamy but not geitonogamy
Column-$III$: $(x)$ Papaya and Date palm, $(y)$ Castor and Maize

Which of the following flowers show heterostyly?