Passage Summary: Since rock climbers often used to be afraid of heights and are now very confident, the act of facing that fear must be what built their confidence.

Conclusion: Confronting one's fears is likely what causes an increase in self-confidence.

Reasoning: People who engage in risky sports often have a history of the very fears those sports confront, and these individuals also display high levels of self-confidence.

Analysis: The argument suffers from a classic correlation-to-causation error. Just because two traits—confronting fear and having confidence—exist in the same person doesn't mean the former caused the latter. To weaken this, look for an answer that suggests the causal arrow points the other direction: perhaps you need high self-confidence *before* you're willing to dangle off a cliff. It’s a bit like assuming that wearing spandex makes you a fast cyclist, rather than realizing fast cyclists simply have a questionable affinity for spandex.