Confusing CR: One way for reducing commuting time for those

[direstraits007]

One way for reducing commuting time for those who work in the cities is to increase the speed at which traffic moves downtown. This can be accomplished by raising the tolls on the tunnels and bridges connecting the city with other communities. This will discourage auto traffic into the city and will encourage people to use public transportation instead.

Which of the following, if true, would LEAST weaken the argument above?

(A) Nearly all of the traffic in the center of the city is commercial traffic which will continue despite the toll increases

(B) Some people now driving alone into the city would choose to car pool with each other rather than use public transportation

(C) Any temporary improvement in traffic flow would be lost because the improvement itself would attract more cars

(D) The numbers of commuters who would be deterred by the toll increases would be insignificant

(E) The public transportation system is not able to handle any significant increase in the number of commuters using the system

source: Arco

OA : B

I didn't find any answer convincing. But, I marked D.

I think the option B is also not that convincing. Bcoz the argument conclusion is to encourage people to use public transportation instead by discouraging auto traffic into the city. The option B says that the people will do pooling, which means that to some extent the auto traffic will come down, but the option B is not even mentioning that people will use public transportation. They will still be using their personal auto's. So overall auto's on the road will be decreased but public transportation is still not encouraged and is still intact. And the claim that public transportation will be encourage is not true in this case too.

So how can B not weaken the argument?

seems like a bad framed question to me.

Thanks.

GeeMate.

[rags99]

In such a question type: degree of weakening of the argument is measured.(1- 100%)

In a least weaken type: any answer choice that strengthens the argument relative to others is the correct choice.

If you compare D and B:

D: If the number of commuters who would be deterred is insignificant...
this weakens the argument that increasing toll will increase commuter speed.

also in GMAT world: insignificant can be : 1 or 2 out of 100 are deterred

B. some ppl will carpool...
in GMAT world: some can be 5-10 out of 100...

so in the relative comparison between B & D, B strengthens the argument , hence it is the correct answer.


any other thoughts.

[RonPurewal]

I think the option B is also not that convincing. Bcoz the argument conclusion is to encourage people to use public transportation instead by discouraging auto traffic into the city. The option B says that the people will do pooling, which means that to some extent the auto traffic will come down, but the option B is not even mentioning that people will use public transportation. They will still be using their personal auto's. So overall auto's on the road will be decreased but public transportation is still not encouraged and is still intact. And the claim that public transportation will be encourage is not true in this case too.

the conclusion of the argument is actually that the given actions will "reduce commuting time" by "increasing the speed at which traffic moves downtown". the public transportation is not the main conclusion of the argument.

if you don't see why this is the case, you can apply the "therefore test": try "X; therefore Y" and "Y; therefore X", and see which one makes sense and which doesn't.
if you apply this technique, your rephrasing of the argument should end with "...therefore commuting time will decrease, and commuters will get into downtown faster."

in light of this fact, (b) will actually strengthen, not weaken, the main conclusion.

--

i'm not sure, however, whether the actual GMAT would do this sort of thing; i.e., i don't know if you would ever be required to pick a statement that strengthens the main conclusion - but does so by circumventing one of the argument's premises (as (b) does here).