Which of the following is NOT one of the four main types of pesticides?

Nutraceuticals are substances that are derived from food sources and are intended to provide health benefits, but they are not classified as pesticides. The four main types of pesticides typically include insecticides, which target insects; herbicides, which are used to kill or inhibit the growth of unwanted plants (weeds); fungicides, which combat fungal infections in plants; and rodenticides, which control rodent populations. Nutraceuticals do not fit into this framework as they do not serve the purpose of pest control, thus making it the correct answer to identify which is not a main type of pesticide. This distinction is important in understanding the various categories and functions of substances used in pest management.