Why is farming particularly difficult for the Maya？ （Text 1A）（）
A. Rivers flood regularly
B. Rain does not sink into the ground
Crops like corn suck nutrients from the soil
D. There are not enough farmers during harvest time
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How did the climate in Angkor change in the 1300s？ （Text 1B）（）
A. Winters became too cool to grow rice
B. Rising temperatures caused great discomfort
C. There were terrible storms and constant flooding
D. Weather conditions became more extreme
Both Sally and Sam receive a 10% raise in a single year. Sally increases her demand for ground beef whereas Sam decreases his demand for ground beef（）
A. This is impossible
B. This is only possible if Sally considers ground beef an inferior good, and Sam views it as a normal good
C. This is only possible if Sally has lower income than Sam
D. This is only possible if Sally considers ground beef a normal good and Sam views it as an inferior good
The slope of the total product curve always equals（）
A. the ratio of the marginal product and the average product
B. the change in input divided by the change in output
C. the average product of the input
D. the marginal product of the input
When the price of a good changes, the income effect can be found by comparing the equilibrium quantities purchased（）
A. on the old budget line and the new budget line
B. on the original indifference curve when faced with the original prices and when faced with the new prices
C. on the new budget line and a hypothetical budget line that is a shift back to the original indifference curve parallel to the new budget line
D. on the new indifference curve
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