What happens when there is a reduction of light during the winter months？
A decrease in melatonin may cause a chemical imbalance.
B. The pineal gland begins functioning to compensate.
C. The retina of the eye opens to receive more light.
D. The mental processes in the brain are slower.
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According to Paragraph 1, guilds in the Late Middle Ages included a system that allowed members to
A. begin as master craftspeople if they had enough skill.
B. progress steadily up the hierarchy in their field.
C. practice more than one craft at a time.
D. exchange goods and services with other craftsmen.
According to the discussion, what reason does the man give for rejecting string theory？
A. There may have been errors in the mathematical calculations.
B. Strings have not been observed in a laboratory.
C. String theory does not prove the theory of everything.
D. The experiments were not performed correctly.
The word its in the passage refers to
A. Catastrophism.
B. planet.
C. England.
D. theory.
Why does the author mention the Louisiana Purchase in Paragraph 1？
A. To discuss how the territories of Ohio and Alabama were added to the nation.
B. To identify the start of Americans' western migration.
C. To explain why pioneers were able to travel to the Mississippi River.
D. To illustrate how America expanded after achieving independence.
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