What defines a pollutant?

A pollutant is defined as a substance that contaminates air, water, or soil, negatively impacting the environment and the organisms that live within it. Pollutants can be harmful chemicals or even materials that, when introduced into the environment, disrupt natural processes and ecosystems. This definition indicates that pollutants interfere with the natural balance of ecosystems, leading to potential harm to both the environment and human health.

The other options describe substances that either contribute positively to natural processes or are beneficial resources, which is contrary to the definition of a pollutant. For instance, promoting growth in natural environments or aiding in plant growth classifies substances that typically enhance ecosystem function rather than degrade it. Additionally, a natural resource that benefits organisms emphasizes the constructive role of certain substances in supporting life, further illustrating the stark contrast with the negative implications of a pollutant.