What is the definition of a pesticide?

The definition of a pesticide is indeed a chemical used to control pests, which encompasses a broad category of substances designed to manage various organisms that can harm crops, livestock, and human health. Pesticides work by targeting insects, weeds, fungi, bacteria, and other pest species, making them crucial in agricultural settings to protect food resources and enhance productivity. This definition aligns with the regulatory perspective on pesticides, which is designed to ensure effective pest management while also considering safety for humans and the environment.

In contrast, the other options touch on aspects that do not define a pesticide. A substance destroyed by bacteria does not inherently imply the substance's function or purpose in pest management. Similarly, simply being any chemical found in pesticides does not capture the essence of what constitutes a pesticide. Regarding fertilization, a product used to fertilize crops serves a different role by enhancing soil nutrient levels rather than directly controlling pest populations. Thus, the focus on pest control distinctly marks option B as the correct and comprehensive definition of a pesticide.