What are the chemicals called that instruct a plant to perform specific actions?

The correct term for the chemicals that instruct a plant to perform specific actions is plant hormones. Plant hormones, also known as phytohormones, play a vital role in regulating various physiological processes in plants, such as growth, development, and responses to environmental stimuli. They can influence processes like cell division, elongation, and differentiation, as well as the timing of flowering and fruiting.

While auxins are indeed a type of plant hormone specifically involved in processes like cell elongation and apical dominance, they are just one category within a broader group of chemicals referred to as plant hormones. Enzymes, on the other hand, are proteins that catalyze biochemical reactions but do not act as signaling molecules like plant hormones do. The term “securols” seems to be incorrectly coined, as it does not correspond to any recognized class of plant chemicals in scientific literature. Thus, the best choice that encompasses the role of these signaling substances is indeed plant hormones.