What is geitonogamy?

Both, autogamy and geitonogamy are prevented in

From among the situations given below, choose the one that prevents both autogamy and geitonogamy.

Assertion : Although geitonogamy is functionally crosspollination involving a pollinating agent, genetically it is similar to autogamy. Reason : In geitonogamy, pollen grains from the anthers of one flower are transferred to the sigma of another flower borne on the same plant.

What is variation? What are its types?