Self pollination is the most economic method for the plant.

Explanation

(1) Self pollination is a sure method of pollination.
(2) Flowers do not depend upon external agents such as wind, insects and water for self pollination.
(3) Self pollination is more economical for the plants as they do not have to develop large and attractive flowers, fragrance, nectar, honey, etc.
(4) There is least wastage of pollen grains during self pollination.