Passage Summary: A researcher noticed that workers wearing back belts get hurt more often than those who don't, so they concluded the belts don't actually work.

Conclusion: Back belts are not an effective tool for preventing back injuries among employees.

Reasoning: A study showed that employees who wear back belts are statistically more likely to be injured than those who do not wear them.

Analysis: The researcher is falling into a classic trap by confusing correlation with causation. They ignore the 'selection bias' inherent in the workplace: the people wearing the belts are likely the ones performing the most dangerous, heavy-lifting tasks. It is a bit like saying that wearing a helmet causes head injuries because people in bike accidents are often wearing helmets. Look for an answer that points out the failure to account for the different baseline risk levels between the two groups being compared.