Which of the following plants strictly exhibits the type of pollination that brings genetically different types of pollen grains to the stigma?

Step-by-step solution

The type of pollination that brings genetically different types of pollen grains to the stigma is xenogamy. For a plant to strictly exhibit xenogamy and prevent both autogamy and geitonogamy, it must be dioecious (bearing male and female flowers on separate plants). Papaya is a dioecious plant, ensuring only xenogamy occurs. Castor and maize are monoecious plants (bearing both male and female flowers on the same plant), which prevents autogamy but allows geitonogamy. Pea is a bisexual plant that naturally undergoes