plzz help me to get out of confusion regarding Unisexuality of flowers prevents

Question

Unisexuality of flowers prevents

A: Geitonogamy, but not xenogamy

B: Both geitonogamy and xenogamy

C: Autogamy, but not geitonogamy

D: Autogamy and geitonogamy

it is often said c but geitonogamy  is also a type of self fertilisation and unisexual plant avoid self pollination

Answer 1

See here autogamy is prevented because each flower only has either male or female organ but geitonogamy can not be prevented because a plant can have both male and female flowers so though geitonogamy is a kind of self pollination its functionally cross pollination without a pollinator you can't perform it.