Passage Summary: Because people on a vitamin regimen get fewer colds, the speaker assumes that anyone who currently has a cold must not be taking those vitamins.

Conclusion: If a person has a cold, they likely do not take daily doses of vitamin C.

Reasoning: People who take daily vitamin C are statistically less likely to catch colds than those who do not.

Analysis: The flaw here is a confusion of group probability with individual certainty. Just because a group is 'less likely' to get sick doesn't mean no one in that group gets sick; it just means they get sick less often. The argument incorrectly assumes that a general trend (fewer colds) can be used to definitively diagnose the habits of a specific individual (the person with a cold). Look for an answer that takes a 'less likely' correlation and treats it as a 'probably not' rule for a specific case.