In which one of the following, both autogamy and geitonogamy are prevented?

1. Autogamy (self-pollination within a flower) is prevented if flowers are unisexual.2. Geitonogamy (pollination between flowers of the same plant) is prevented if the plant is dioecious (male and female flowers on different plants).Papaya is a dioecious plant, so it prevents both. Castor and Maize are monoecious (separate male/female flowers on same plant), so they prevent autogamy but not geitonogamy.