Passage Summary: Old cities needed a lot of food, which meant farming. Farming needed water for irrigation, and back then, you could only irrigate if you were close to a river or lake.

Reasoning: Urban density requires large-scale farming; large-scale farming requires irrigation; irrigation requires proximity to water.

Analysis: This stimulus sets up a conditional chain that we can follow to a logical destination. If urban societies require large-scale farming, and that farming requires irrigation, and irrigation was only possible near water, then early urban societies were essentially tethered to water sources. You should look for an answer choice that synthesizes these requirements to conclude that early cities were located near rivers or lakes. Don't look for new information; just look for the logical result of the facts provided.