Passage Summary: Coffee can hurt your stomach because of caffeine, but dark roasts have a special chemical called NMP that actually helps settle the stomach. Because dark roasts have more of this 'good' chemical than light roasts do, the author claims dark coffee is the better choice for your digestion.

Conclusion: If you're a coffee drinker, choosing a dark roast will result in less stomach irritation than choosing a light roast.

Reasoning: Caffeine increases stomach acid, but dark roasts contain higher levels of NMP, a substance that suppresses stomach acid, compared to light roasts.

Analysis: The author is comparing two opposing forces: the irritating effect of caffeine and the soothing effect of NMP. The argument assumes that the extra NMP in dark roast is enough to make it 'less irritating' overall. But what if dark roast also has way more caffeine than light roast? If the 'bad' stuff increases more than the 'good' stuff, the conclusion fails. To evaluate this, we need to know the relative levels of caffeine in both roasts. Look for a question that asks about the caffeine content or other potential irritants in the two types of coffee.