What is a growth regulator?

A growth regulator is a chemical that alters the growth process of a plant or animal, which is essential in both agricultural and horticultural applications. These substances can influence various physiological processes such as growth, flowering, and fruiting, and they can be used to enhance specific traits or manage the timing of growth events. For instance, in plants, growth regulators can be applied to promote or inhibit flowering, control fruit drop, or shape plant growth, thus improving crop yields and quality.

The other options do not accurately define a growth regulator. While killing insects is associated with insecticides, and destroying weeds relates to herbicides, these do not encompass the growth-altering functions of growth regulators. Furthermore, a material that does not dissolve in liquid pertains to solubility characteristics and does not relate to the concept of influencing growth processes. Thus, the definition that encapsulates the unique role of growth regulators is indeed that they serve as chemicals that alter the growth processes of plants or animals.