Define a persistent pollutant and give an example.

• A. Persistent pollutants resist degradation and remain in the environment for long periods; example: DDT or PFAS.
• B. Persistent pollutants are those that degrade quickly; example: nitrate.
• C. Persistent pollutants are only natural materials like sandstone.
• D. Persistent pollutants only affect air but not water.

Answer: (A)

The idea being tested is persistence: a pollutant is persistent if it resists degradation by light, microbes, and chemical processes, so it stays in soil, water, and even living organisms for long periods. The best choice captures this by saying persistent pollutants resist degradation and remain in the environment for long periods, with examples like DDT or PFAS. That matches what scientists mean by “persistent” and why these substances linger for years or decades.

Why this works: DDT and PFAS are well-known for their chemical stability. PFAS, in particular, have very strong carbon–fluorine bonds that are hard to break, which is why they’re often referred to as “forever chemicals.” That stability translates to long-lasting presence in the environment and potential to move through air, water, and ecosystems.

Why the other descriptions don’t fit: a pollutant that degrades quickly is the opposite of persistent, so that option wouldn’t be correct. Natural materials like sandstone are not pollutants at all, so they don’t describe persistent pollutants. And restricting a pollutant to affect only air ignores the real behavior of many persistent pollutants, which can spread through air, water, and soil and stay in those environments for long periods.