Several thousand years ago, people in what is now North America began to grow corn, which grows faster and produces more food per unit of land than do the grains these people had grown previously. Corn is less nutritious than those other grains, however, and soon after these people established corn as staple grain, although they could have returned to growing the more nutritious grains.
What this question is testing
Your task
Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.
Common trap
Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.
Winning move
Predict what a right answer must do, then test each choice against the conclusion-evidence gap.
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