Reading inference — cross-border pollutants and banned insecticides A paragraph notes there are no effective boundaries for pollutants. Toxic insecticides banned in many countries ride the wind from places where they remain legal; compounds like DDT and toxaphene have been detected even in the Yukon and other Arctic regions. Which statement is best supported?

Introduction / Context:
The passage highlights atmospheric transport of pollutants and mentions that some toxic insecticides banned in many countries are still legal in others, resulting in global spread. The question asks for the statement most directly supported by these facts.

Given Data / Assumptions:

• Pollutants cross borders; wind can carry them long distances.
• Some toxic insecticides have been banned in many countries but remain legal elsewhere.
• DDT and toxaphene residues are found even in remote Arctic regions.

Concept / Approach:
Choose the option that restates an explicit claim from the text: that bans are not universal. Avoid options that generalize beyond the evidence (e.g., about relative pollution levels in climates) or that add unsupported claims (e.g., world’s most toxic).

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

• B: The passage does not compare polar vs. warm areas quantitatively.
• C: It does not say countries ignore their own laws; it says some countries still legally allow the chemicals.
• D: “Most toxic” is not claimed.
• E: A worldwide ban’s hypothetical effect is not discussed.

Common Pitfalls:
Mistaking “found in the Arctic” for “more in the Arctic,” or reading policy predictions into a descriptive text. Stick to the explicit statement about non-universal bans.

Final Answer:
toxic insecticides such as DDT have not been banned throughout the world.