Read the excerpt from "Machu Picchu: A City in the Sky."

"The soil needed water for growing crops. The farms got water from mountain snow. The Incas built an aqueduct to carry the water down the mountain. The aqueduct was made up of stone channels. Water flowed down the mountain through these channels. The water was used to irrigate the farmland. Scientists today admire the system the Incas built to irrigate the land."

What is the central idea of the excerpt?

A. When the Incas wanted to grow crops, they knew the crops needed water.

B. The Incas built an aqueduct to use mountain snow to irrigate their farms.

C. The Incas used their resources when they dug up stones to build structures.

D. When the Incas irrigated farms, Inca scientists studied the results.

The central idea of the excerpt is that the Incas designed an aqueduct system to use water from mountain snow for irrigation of their crops. This engineering achievement highlights their innovative approach to agriculture. Modern scientists admire this irrigation system for its effectiveness and ingenuity.

Explanation:

Central Idea of the Excerpt

The central idea of the excerpt focuses on the ingenuity of the Incas in managing water resources for agriculture. The text highlights how the Incas built an aqueduct system to transport water from mountain snow to their farms, which was crucial for irrigation and supporting their agricultural needs.

Specifically, it emphasizes that the Incas constructed a network of stone channels that allowed the snowmelt to flow efficiently down the mountain to irrigate their croplands. This engineering feat is noted for its effectiveness, which modern scientists still admire today for its sophistication. Thus, the most accurate central idea from the options given is: The Incas built an aqueduct to use mountain snow to irrigate their farms.

Learn more about Inca irrigation here:

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