The correct option is B Autogamy and geitonogamy
Plants in which male and female flowers are present on different plants are sid to be dioecious. Example - Papaya.
This condition prevents autogamy (self pollination within the same flower), geitonogamy (self pollination between different flowers of the same plant) and cleistogamy (self pollination in closed flowers)
It promotes xenogamy or cross pollination.