Both, autogamy and geitonogamy are prevented in -
Papaya
Cucumber
Castor
Maize
Self-pollination is a type of self-pollination that occurs in a flower.Geitonogamy is another type of self-pollination which occurs between different flowers of the same plant.Now, according to the question, the above two processes take place, which shows that in this plant, the male and female flowers are located on separate plants, dioecious plants.The papaya tree is a dioecious plant. Hence, option 1 is correct.