When the pollen grains are not transferred from anthers to the stigma in flower due to the barrier or fence, it is referred or when some natural barrier exists between androecium and gynoecium to check self pollination, it is known as _____________.
Herkogamy is a probable strategy applied by hermaphroditic angiosperms to reduce sexual interference between male and female function. It varies from other such strategies by supplying a spatial parting of the anthers and stigma.
Heterostyly is referring to the condition of having styles of different lengths, These are relative to the stamens in the flowers of various individual plants for reducing self-fertilization.
Dichogamy is the condition in which the male and female reproductive organs of the flower mature at different times to ensure that self-fertilization does not occur.
Cleistogamy refers to the self-fertilization which occurs within a permanently closed flower.
So option B is correct.