Any material, or form of energy, that will cause harm to a living organism.

• A. Hazard
• B. Contaminant
• C. Toxin
• D. Pollutant

Answer: (D)

Harmful effects on living organisms from substances or forms of energy.

A pollutant is any material or energy introduced into the environment that can cause harm or degrade quality. It covers a wide range, including chemicals, particulates, and even non-chemical energy like loud noise or radiation. That broad scope fits the idea of “any material or form of energy that will cause harm,” because it uses the presence of a harmful agent to explain the impact on living things.

A contaminant is an unwanted substance in a system, but it doesn’t always imply harm by itself; it can be present without causing damage in some contexts, whereas a pollutant is defined by its potential to cause harm. A toxin is a harmful substance, typically produced by living organisms; it’s a subset of pollutants when present in the environment, but not every pollutant is a toxin. A hazard refers to the potential to cause harm, not the actual presence of a harmful agent in the environment. So the term that best captures the idea of any material or energy form that will cause harm is pollutant.