Passage Summary: Some doctors want to pull a highly effective asthma drug off the market because one-fifth of the people who took it had severe negative reactions.

Conclusion: Asthmagon should be banned as a treatment for asthma.

Reasoning: A six-year study showed that approximately 20 percent of patients using the drug experienced serious side effects.

Analysis: To weaken this argument, we need to find a reason why a 20% side-effect rate might actually be acceptable. The argument assumes that the risks of the drug outweigh its benefits or that there are safer, equally effective alternatives available. Look for an answer choice that provides context—perhaps the 'serious side effects' are still less dangerous than the life-threatening asthma attacks the drug prevents, or maybe other available drugs have even higher rates of side effects. We want to find a fact that makes the proposed ban seem like a net negative for patients.