Hint:The process which leads to the fertilization in plants is known as pollination. It is the transfer of male gametes present inside the pollen grains near to the female gamete, with the help of various agents such as wind, water, and animals.
Complete answer:When the fertilization occurs by the pollen is transferred from one flower to another flower that belongs to the same plant, the process is known as geitonogamy. It is a process of self-pollination since fertilization occurs between the gametes produced by the same plant. This type of fertilization can be seen in monoecious plants such as maize, which consists of both male and female flowers.
Considering other options:
When the pollination occurs between the flowers present in different plants, the process is known as xenogamy and it is known as cross-pollination. It helps in the development of a new variety since a cross-fertilization is involved. The process is dependent upon various pollinators be it biotic or abiotic.
Also from the given options,
Hence, the most appropriate one was found to be A, that is geitonogamy happens when fertilization occurs when pollen of a flower is transferred to another flower of the same plant.
Note:Autogamy occurs when the pollination occurs between the anther and stigma of the same flower. It is also known as self-pollination. The anther and stigma will be in a synchronized state for effective pollination. Self-pollination is the only effective method of pollination in cleistogamous flowers, which are closed, and they don’t require a pollinating agent for the process.