A cost-effective solution to the problem of airport congestion is to

Passage Analysis:

A cost-effective solution to the problem of airport congestion is to provide high-speed ground transportation between major cities lying 200 to 500 miles apart.

• Problem: Airport congestion.
• Cost-effective solution: High speed ground transportation between major cities spaced between 200 to 500 miles.

The successful implementation of this plan would cost far less than expanding existing airports and would also reduce the number of airplanes clogging both airports and airways.
Advantages of successful implementation of this solution:

• Much lower cost compared to expanding existing airports.
• Reduces the number of airplanes clogging both airports and airways.

Question stem

Which of the following, if true, could proponents of the plan above most appropriately cite as a piece of evidence for the soundness of their plan?

The question essentially asks for a strengthener.

Pre-thinking

The conclusion here is that high-speed ground transportation between major cities lying 200 to 500 miles apart will provide a cost effective solution to the problem of airport congestion.

To strengthen this conclusion, we can give details that state either

• ground transport development of this kind is less costly,
  or that
• the chance for the ground transport being opted by travellers is higher,

for example.

Option Analysis

(A) An effective high-speed ground-transportation system would require major repairs to many highways and mass-transit improvements.
This is a weakener since it states that developing high-speed ground-transportation system will be costly. It is against the conclusion. Hence it is incorrect.

(B) One-half of all departing flights in the nation’s busiest airport head for a destination in a major city 225 miles away.
This option is in the line of our second strengthener. If half of the flights that use the busiest airport have a destination that can be covered by a high-speed ground-transportation system , then the likelihood that people shift to the alternative option is higher. It will be cost effective since it is to the same city and it can effectively reduce the air traffic at the airport almost by half. Therefore it is the correct answer.

(C) The majority of travelers departing from rural airports are flying to destinations in cities over 600 miles away.
This option talks about rural airports which are presumably not very congested. Also, this talks about a situation where high-speed ground-transportation system are not useful or relevant, so if anything this option can only weaken the conclusion.

(D) Many new airports are being built in areas that are presently served by high-speed ground-transportation systems.
We are talking about existing airports that experience congestion and not the ones that are newly being made. New airports being built in areas serves by high-speed ground-transportation system does not bring in any causative effect into the equation.

(E) A large proportion of air travelers are vacationers who are taking long-distance flights.
Again. long distance flights imply that the high-speed ground-transportation system may not be of muh use for the vacationers. Hence this option also has a weakening effect.

Therefore the correct answer is B