The correct option is A Pollination agent is not required
Cleistogamous flowers do not open at all. In such flowers, the anthers and stigma lie close to each other. Anthers when dehisce in the flower buds, pollen grains come in contact with the stigma to effect pollination. Thus, cleistogamous flowers are autogamous as there is no chance of cross-polliation. So, no pollination agent is required in these flowers.