What are pollutants?

Pollutants are defined as substances that contaminate the environment, specifically air and water, and can cause harm to living organisms. This definition encompasses a wide range of chemicals, biological agents, and physical phenomena that negatively impact air and water quality, leading to adverse health effects, ecosystem disruption, and degradation of natural resources.

When considering the context of this definition, it becomes clear why the concept of pollutants is closely related to harmful impurities. Pollutants can originate from various sources, including industrial emissions, vehicle exhaust, agricultural runoff, and waste disposal, each contributing to environmental issues that can affect both human health and biodiversity.

In contrast, the other choices focus on concepts that do not encompass the definition of pollutants. Natural resources refer to materials that are found in nature and used for economic gain, while the process of resource allocation deals with how resources are distributed among people or sectors. Types of renewable resources specifically refer to energy sources that can be replenished naturally over time, and do not inherently involve pollution or harmful substances. Therefore, the only option that accurately describes pollutants is the one focusing on impurities in air and water that are detrimental to life.