A city councilor argues that banning privately owned cars from

Question

A city councilor argues that banning privately owned cars from the downtown area will substantially reduce the city’s overall air pollution levels. The councilor reasons that since privately owned cars account for a majority of vehicle traffic downtown, eliminating them from that area will significantly lower pollution citywide.

Which of the following, if true, most seriously weakens the councilor’s argument?

Which of the following, if true, most seriously weakens the councilor’s argument?

(A) Commercial delivery vehicles, which would still be permitted downtown, emit substantially more pollutants per vehicle than privately owned cars.
(B) Cities that have banned privately owned cars downtown have experienced economic growth in surrounding neighborhoods.
(C) Many commuters who currently drive privately owned cars downtown would instead switch to public transportation.
(D) Air pollution levels in the city have declined slightly in recent years despite an increase in downtown traffic.
(E) Residents living outside the downtown area contribute more to total vehicle miles traveled than downtown commuters.

guddo · Answer

A city councilor argues that banning privately owned cars from the downtown area will substantially reduce the city’s overall air pollution levels. The councilor reasons that since privately owned cars account for a majority of vehicle traffic downtown, eliminating them from that area will significantly lower pollution citywide.

Which of the following, if true, most seriously weakens the councilor’s argument?

Which of the following, if true, most seriously weakens the councilor’s argument?

The argument treats “most downtown vehicles” as if it means “most of the pollution that matters for the whole city.” I’d say the best weakener shows that private cars are not the main source of emissions downtown, so removing them would not cut pollution by much.

A. Commercial delivery vehicles, which would still be permitted downtown, emit substantially more pollutants per vehicle than privately owned cars.

This most seriously weakens. Even if private cars are most of the traffic, they might contribute less of the emissions if delivery vehicles pollute far more per vehicle. Then removing private cars removes a lot of vehicles but not necessarily a lot of pollution. That breaks the key link from “majority of traffic” to “big citywide pollution drop.” This is exactly  traffic share is not emissions share .

B. Cities that have banned privately owned cars downtown have experienced economic growth in surrounding neighborhoods.

This is about economic outcomes, not air pollution. It does not challenge the pollution reasoning.

C. Many commuters who currently drive privately owned cars downtown would instead switch to public transportation.

This supports the argument because it suggests fewer private cars will be driven, which would tend to reduce emissions.

D. Air pollution levels in the city have declined slightly in recent years despite an increase in downtown traffic.

This shows other factors also affect pollution, but it does not show that banning private cars downtown would fail to reduce pollution.

E. Residents living outside the downtown area contribute more to total vehicle miles traveled than downtown commuters.

This suggests a lot of driving happens outside downtown, but it does not directly show that the downtown private car ban would not reduce emissions substantially. It is weaker than (A), which directly targets the councilor’s central assumption.

Answer: (A)

egmat · Answer

The Argument: 
The councilor claims: Banning private cars downtown →  substantially  reduce  citywide  air pollution.

Why? Because private cars are the  majority  of downtown traffic.

The Hidden Assumption: 
The councilor assumes that  more vehicles = more pollution .

But  this is the trap!  Being the majority of  vehicles  doesn't mean being the majority of  pollution .

Why (A) Destroys the Argument: 
Commercial delivery vehicles:
- Will  still be permitted  downtown
- Emit  substantially more pollutants per vehicle

Think of it this way: 
-  100  private cars ×  1  unit pollution each =  100  units
-  20  delivery trucks ×  10  units pollution each =  200  units

Even after removing all  100  cars, the  200  units from trucks remain!

So banning private cars may  not  substantially reduce pollution at all.

Why Other Choices Fail: 
(B) Economic growth →  Irrelevant  to pollution
(C) Switching to public transit → Actually  strengthens  the argument!
(D) Past pollution trends → Doesn't address this specific policy
(E) Miles traveled outside downtown → Doesn't weaken downtown ban's effect

Here, the assumption is that vehicle COUNT determines pollution levels. Answer (A) shows that pollution PER VEHICLE matters more.

Answer: A

Usernamevisible · Answer

(D) is weaker because it does NOT isolate private cars as the cause of pollution.

(D) says:
> Air pollution declined slightly despite increased downtown traffic.

But this does NOT prove:
> “Private cars do not significantly contribute to pollution.”

Why?
Because many other factors could have reduced pollution at the same time:
* cleaner factories
* better fuel standards
* cleaner engines
* reduced industrial emissions

D gives a trend, but correlation does not mean causation.

GMAT rule:
> “Despite X increasing, Y decreased”
> is weak causal evidence unless other factors are controlled.

(A) is stronger because it attacks the exact assumption directly.

Councilor assumes:
> most traffic = most pollution
(A) says:
> wrong — remaining commercial vehicles emit far more pollution per vehicle.

So even if private cars are the majority of traffic, they may NOT be the majority source of pollution.

iamjayysingh · Answer

but wht if there is only 1 commercial delivery vehicle?

guddo · Answer

If there were  only 1 commercial delivery vehicle , then A would weaken much less.

But the option does not say there is only one. It refers to “commercial delivery vehicles” as a continuing category downtown.

So we should not add the extreme assumption “only one.” Under the option as written, A weakens because even if private cars are most vehicles, the remaining delivery vehicles could still produce a large share of pollution  per vehicle .

TheYagami · Answer

Option A only weakens the assumption that (most traffic equals most pollution), but it does not necessarily undermine the conclusion that banning private cars would significantly reduce pollution.
 
Even if delivery vehicles pollute more per vehicle, privately owned cars could still contribute a substantial share of total pollution, so removing them may still significantly lower citywide pollution.

A city councilor argues that banning privately owned cars from

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A city councilor argues that banning privately owned cars from

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