Passage Summary: We think HDLs are healthy because people who exercise and women—both of whom have high HDL levels—tend to have fewer heart problems.

Conclusion: High-density lipoproteins (HDLs) likely help prevent heart disease and stroke.

Reasoning: There is a correlation between factors that raise HDL levels (exercise, being female) and a lower risk of heart disease.

Analysis: This is a 'Strengthen EXCEPT' question, meaning four choices will support the link between HDLs and heart health, and one will not. The argument relies on a correlation-to-causation jump. To strengthen it, we want to see evidence that HDLs themselves are doing the work or eliminate other variables. The correct answer will either be irrelevant to the conclusion or potentially weaken the connection.