10
 Why was corn or maize grown at
 the lower levels of the Andes
 Mountains, but potatoes were
 grown near the top?
 A. The temperature was colder at the bottom of
 the mountains.
 B. The temperature was warmer at the bottom of
 the mountains.
 C. Corn did not need soil to grow.
 D. Most corn crops needed less water than
 potatoes.