Which term describes a chemical used to control pests?

The term "pesticide" is a broad classification that encompasses any chemical used to control a variety of pests, including insects, weeds, fungi, and other organisms that can be harmful to plants and human activities. This term is the umbrella under which more specific types of chemicals fall, such as insecticides, herbicides, and fungicides.

Insecticides specifically target insect pests, herbicides aim at controlling unwanted plants (weeds), and fungicides are designed to combat fungal infections. While these specific types of chemicals serve important functions, "pesticide" is the overarching term that accurately captures all chemical agents intended for pest management, making it the most correct answer in this context.