Which of the following is an example of a chemical contaminant?

A chemical contaminant refers to harmful substances that can adversely affect health and the environment, typically resulting from human activities or industrial processes. Pesticides fit this definition as they are chemical substances designed to kill pests. When they enter the environment, they can contaminate water, soil, and even food, posing risks to human health and ecosystems.

In contrast, soil particles are solid materials found in the environment, but they do not have toxic chemical properties in the context of contamination. Algae, while they can indicate water quality issues and can produce toxins, are biological organisms rather than chemical contaminants. Bacteria, similar to algae, are living microorganisms and represent a type of biological contamination. Thus, pesticides stand out as the clear example of a chemical contaminant in this context.