PrepTest 148, Section 2, Question 7

Working the answers

• A

  This is the opening fact, almost word for word. It establishes the event that needs explaining but does not tell us why migration continued as the income gap narrowed.

• B

  These are important starting causes. The authors accept them, then move on to a different question: why did migration continue over the following decades? B stops before their central contribution.

• C

  This is tempting because it connects earlier migrants’ help with continued migration. But it reduces that help to defraying financial costs. The explanation also includes information, reduced uncertainty, and help adjusting to unfamiliar surroundings. C makes one part of the mechanism stand for the whole. “Accelerated” is not the problem; the second paragraph expressly says migration “even accelerated.”

• D

  This captures part of the proposed mechanism, but leaves out the particular puzzle it explains: the Great Migration continued while the original income incentive was shrinking. A general statement about migration movements does not capture that full argument.

• E
  Correct

  This gives the overall contrast we predicted: the income differential explains the beginning, but additional factors explain the long continuation. E does not list the network effects, but its broader wording makes room for all of them instead of narrowing the explanation to financial help alone.