Passage Summary: Researching products is hard work. You're only being rational if you skip the research when the effort isn't worth the reward. Therefore, people who skip the research are being rational.

Conclusion: Consumers who choose not to gather complete information about a product are acting rationally.

Reasoning: It is difficult and expensive to get full product info, and it is only rational to do so if the benefits of the info outweigh those costs.

Analysis: The argument provides a condition for when it is rational *not* to acquire information (when costs > benefits). However, it concludes that consumers who don't acquire information are *definitely* being rational. This assumes that for these specific consumers, the costs actually do outweigh the benefits. To make this conclusion follow logically, we need a 'Sufficient Assumption' that guarantees the condition was met. Look for an answer that states the cost and difficulty of getting this information generally outweigh the benefits for these consumers.