Choose the statement that is best supported by the information given in the…

Concept: A "best supported by the passage" question asks for the one claim that follows directly from what the text states - not an inference, comparison, or ranking that needs information the passage does not give.

Application: The passage says toxic insecticides banned in many countries are "riding the wind from countries where they remain legal." That single fact establishes that these insecticides are still legal somewhere in the world - that is, they have not been banned everywhere - which is exactly the claim that toxic insecticides such as DDT have not been banned throughout the world.

Cross-check: Checking the passage for anything else it establishes: it gives Arctic locations only as examples of where residues have been found, never comparing quantities with warmer regions; it describes insecticides remaining legal elsewhere, not any country breaking its own law; and it names DDT and toxaphene only as compounds detected far from their source, never ranking their toxicity. None of those other readings is supported without adding information beyond the text, confirming the one claim that is directly stated.

Contrast with the other options:

• toxic insecticides such as DDT have not been banned throughout the world - directly stated: the passage says these compounds remain legal in some countries, so this holds without any added inference.

• more pollutants reach polar climates than warmer areas - the passage gives Arctic examples but never compares quantities between climates, so this goes beyond the text.

• many countries have ignored their own antipollution laws - the passage shows the insecticides remain legal in some countries, meaning no law is being ignored there.

• DDT and toxaphene are the two most toxic insecticides in the world - the passage cites them only as substances found in remote regions, not as part of a toxicity ranking.