Question

For years the beautiful Renaissance buildings in Palitito have been damaged by exhaust from the many tour buses that come to the city. There has been little parking space, so most buses have idled at the curb during each stop on their tour, and idling produces as much exhaust as driving. The city has now provided parking that accommodates a third of the tour buses, so damage to Palitito's buildings from the buses' exhaust will diminish significantly.
Which of the following, if true, most strongly supports the argument?

• A. The exhaust from Palitito's few automobiles is not a significant threat to Palitito's buildings.
• B. Palitito's Renaissance buildings are not threatened by pollution other than engine exhaust.
• C. Tour buses typically spend less than one-quarter of the time they are in Palitito transporting passengers from one site to another.
• D. More tourists come to Palitito by tour bus than by any other single means of transportation.
• E. Some of the tour buses that are unable to find parking drive around Palitito while their passengers are visiting a site.

Hint:

In questions that ask you to strengthen a plan's predicted outcome, look for the answer choice that confirms the plan will effectively address the most significant part of the problem. Here, the problem is exhaust, and option (C) confirms that the plan targets the main source of that exhaust: idling during long stops.

Answer 1

The Correct Option is C

Step 1: Understanding the Argument
The argument presents a plan and predicts its success.
Problem: Tour bus exhaust damages buildings. A major source of this exhaust is buses idling at the curb.
Plan: Provide new parking for one-third of the tour buses.
Conclusion: Damage from bus exhaust will diminish significantly.
Assumption: The argument assumes that providing parking for one-third of the buses will lead to a significant reduction in total idling time for the entire fleet of buses.

Step 2: Analyzing the Task
We need to find an option that strengthens the conclusion. A good strengthener will often bolster a key assumption or provide additional evidence that the plan will be effective. We need to show that idling is indeed the main problem that the new parking will address.

Step 3: Evaluating the Options
(A) This option rules out automobiles as a major source of exhaust damage. By eliminating an alternative cause, it slightly strengthens the focus on buses as the primary problem, thus making a plan to address bus exhaust more likely to be significant. However, it's a weak strengthener.
(B) Similar to (A), this rules out other forms of pollution. It strengthens the focus on engine exhaust, but doesn't specifically strengthen the link between the new parking and the reduction in that exhaust.
(C) This option provides crucial information about the buses' behavior. If buses spend less than 25% of their time driving and, by implication, more than 75% of their time stopped (and previously, idling), it means that idling is the predominant activity. Therefore, a measure that reduces idling for a third of the buses will have a very large impact on the total amount of exhaust produced. This directly and strongly supports the conclusion that the damage will "diminish significantly."
(D) This option establishes that tour buses are a major source of tourists, which in turn implies they are a major source of pollution. This supports the premise that bus exhaust is a problem, but it doesn't strengthen the link between the specific solution (parking) and the outcome (less damage). We already know the exhaust is a problem.
(E) This option weakens the argument. It suggests that buses unable to find parking might create even more exhaust by driving around than they would by idling. This suggests the new parking, which is only for one-third of buses, might not solve the problem and could even make it worse for the other two-thirds.
Step 4: Final Answer
Option (C) is the correct answer because it quantifies the importance of idling. By showing that buses are stationary (and thus potentially idling) for the vast majority of their time in the city, it demonstrates that the new parking, which targets this specific activity, will have a significant effect.