Solution:

Auxins promote stem elongation, inhibit the growth of lateral buds (maintains apical dominance). They are produced in the stem, buds, and root tips. Example: Indole Acetic Acid (IA).

Cytokinins are plant hormones that cause increased cell division by stimulating the process of mitosis. They are made naturally by plants but have been synthesized by humans. Increased mitosis results in plant growth and the formation of shoots and buds, as well as the development of fruits and seeds.

Ethylene serves as a hormone in plants. It acts at trace levels throughout the life of the plant by stimulating or regulating the ripening of fruit, the opening of flowers, and the abscission (or shedding) of leaves.

Gibberellins are growth hormones that stimulate cell elongation and cause plants to grow taller. Gibberellins also have a role in other plant processes, such as stem elongation, germination, flowering, and fruit ripening.