The correct answer is that during cross-pollination the pollen grains are carried from one plant to another plant. During self-pollination, the pollen and ovules are from the same plant.
In self-pollination, the pollen from the anther is deposited on the same flower's stigma, or on the stigma of another flower of the similar plant. In comparison, out-crossing or cross-pollination results in greater genetic diversity as the pollen grains and ovules are obtained from different plants.