Both autogamy and geitonogamy are prevented in
(A) Papaya
(B) Cucumber
(C) Castor
(D) Maize

Dear student,

The correct option is A - 
Autogamy and geitonogamy are prevented in Papaya because papaya is a dioecious plant where both male and female flowers are separate. 
Autogamy - It means the self-pollination, pollen grains of one flower sheds on the stigmas of the same flower. So it is exempted from papaya.

Geitonogamy - When the pollen grains of one flower transfers to the stigma of different flower in the same plant. It is also not possible in papaya.

Regards.