Which statement best defines pollution?

• A. The presence of undesirable factors or pollutants added to air, water, or soil
• B. The natural cleaning process of environments
• C. The chemical reaction between acid and base
• D. The method of treating wastewater with salts

Answer: (A)

Pollution means introducing undesirable factors or pollutants into air, water, or soil, which degrades the environment and can harm living things. This definition focuses on those added substances or conditions that make the environment less clean or safe. It isn’t about the environment’s natural cleaning processes, which remove pollutants, nor about a chemical reaction like acid and base blending, which is unrelated to defining pollution. It also isn’t describing a wastewater treatment method, which is meant to reduce pollution rather than define it.