PrepTest 110, Section 2, Question 2

What we’re looking for

Working the answers

• A

  This supports the goal of investing in an efficient, attractive system. It still doesn't tell us what the investment requires. Perhaps the city could improve the system while retaining its existing cars. We need a connection to the purchase, not another statement in favor of the overall goal.

• B

  Cost-effective cars aren't necessarily new cars. The city might already have cost-effective cars, or its proposed new ones might be expensive to operate. Even if such cars are essential to an efficient system, B doesn't establish that the city needs to purchase new ones.

• C

  Being better than many other investments doesn't establish that this purchase makes good economic sense. It could be better than several bad options and still be a bad option itself. Nor does the comparison show that new cars are required to achieve the efficient, attractive system. C offers a ranking without supplying the missing requirement.

• D

  Being able to afford something doesn't mean you need to buy it. The city could have enough money for new cars while the existing cars already do the job. D removes a possible financial obstacle without establishing the reason for the purchase.

• E
  Correct

  This directly connects the new cars to the desired system. The city should have an efficient, attractive subway because that makes good economic sense. E says new cars are required for that system. So the city needs new cars to do what the premises say it should do.

  The direction matters: this isn't just a claim that new cars could produce a good system. It says the city cannot have the specified system without them. That is what justifies calling the purchase necessary.