Passage Summary: A tiny study found that young people have fewer banned chemicals in their bodies than older people. Even though the study was too small to be scientific, the author claims it proves the ban worked.

Conclusion: The 1970s ban on PCBs was effective in reducing human exposure.

Reasoning: In a small 2005 study, younger participants (born after the ban) had lower levels of the chemicals than older participants.

Analysis: The author explicitly admits the study is too small for 'scientifically valid inferences' but then immediately draws a massive, definitive conclusion from it. This is a blatant self-contradiction. Furthermore, the age difference could be explained by bioaccumulation—older people have simply had more years to absorb chemicals—rather than the ban itself. Look for an answer that points out the sample size issue or the alternative explanation for the age gap.