A.Plant growth, development and responses to the environment is controlled and coordinated by a special class of chemical substances known as hormones. 

B.Hormones are produced in one part of the plant and are transported to all the needy parts of the plant. 

C.The five major types of phytohormone are auxins, gibberellins, cytokinins, abscisic acid, and ethylene. 

D.These phytohormones are either growth promoters or growth inhibitors such as abscisic acid.