If central business districts were restricted to commercial

Yes you are correct the main conclusion is the second sentence. Conclusion is normally provided in the end after all reasoning however what you are missing is that there can be multiple conclusion in one argument and one conclusion can be used to support the main conclusion of the passage.

This is what is happening in the passage above.
Hope this helps

My answer is C.
We should find an assumption which follows to the fact that personal cars will not enter central districts in the case if there is a ban for commercial ones (1st sentence's conclusion). The only assumption underlying the connection between personal cars and commercial cars is C.
A,B - any infrastructure can not affect relation between personal / commercial
D,E - congestion is discussed in the 2nd premise and has nothing to do with the 1st one.

Agreed. But if we consider the second statement to be the conclusion, then wont D be a contender?

Hi - To me this comes into the category of 'not worth worrying about' - a massive key thing on GMAT is just focussing on the Question.

It explicitly says the first sentence is the conclusion you should be looking for - so look for it there!

Don't distract yourself.

James

When I assume that the whole 1st sentence is evidence (the downtown is banned for commercial vehicles & personal cars don't enter the urban centers) and 2nd sentence is conclusion (reduced traffic leads to the decrease of congestions/collusions in the downtown) then my logic is:
personal cars do the most congestions/collusions (D assumption) - > but the commercial cars (not personal ones) are banned - > no definite impact on the situation in the urban districts

James, would you please explain why D can not be the answer here?

Action:Restrict central business districts to commercial traffic.

Conclusion: most personal cars would not enter urban centers.

To reach this conclusion we are missing the link that will explain why traffic restriction will lead to most personal card not entering urban centers.

First, identify the Question: restrict traffic to commercial + ???? = most personal cars would not enter.

'C' gives the answer > Most personal cars aren't used for commercial purposes, hence traffic restriction directly affects decrease in personal cars entering the area.

While 'E' reads as following:

most personal cars would not enter + ???? = increase in commercial traffic.

As you can see, this answer not only doesn't provide any assumption as required by the original question, but also misses an assumption itself. Why would decrease in personal cars to the area lead to an increase in commercial traffic? there's a link missing.

Same here. James can you explain why D is not correct answer choice?

Thanks
Cheers
J

+1 for D....
source and OA please??

Answer is C
We need to remember that Assumption answers must provide new information.
In this question te conclusion is that the Ban in personal cars will reduce traffic.
So the author assumes that no personal cars are used for commercial purposes..
If they are the conclusion falls apart,I.e. The ban will not reduce traffic (The negation technique can be applied)

The option which says the most cars cause accidents and congestion is not an assumption but an inference or precisely a must be true ..this information is inferrable from the passage,and it does not provide new Information

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First sentence: "If central business districts were restricted to commercial traffic, which includes taxis and buses, most personal cars would not enter urban centers"
- There is a clear assumption here. That is, personal cars do not belong to commercial traffic type. So, a limit use to only commercial traffic will exclude the appearance of personal cars. Answer C (as the official fits very well).



Second sentence, also the conclusion: "Such a reduction in traffic would reduce the risk of congestion and collisions in central business districts"
- "Such a reduction in traffic" equally means that "such a reduction in the appearance of personal cars". and this will reduce the risk of congestion and collisions. Problems appear: why does the reduction of personal cars help to reduce the risk of congestion and collisions in central business districts?

- Doubtless there are two assumptions:
1) Personal cars must have contributed to the increasing risk congestion and collisions in central business districts, and a reduction in personal cars will reduce such risk.
- However, logically, we have the pattern: A causes B. Then, Not A DOES NOT NECESSARILY mean Not B.
- Therefore, the reduction in personal cars does not guarantee that the risk of congestion and collisions is reduced UNLESS it rests upon the second assumptions:

2) Between commercial traffic and personal cars, the former will cause less (or even no) risk of congestion and collision THAN personal cars. At that time, when there is much less appearance of personal cars and mostly the appearance of commercial traffic, the risk of congestion and collision WILL BE reduced.
- Such assumption is equally to: "Personal cars are more likely to cause congestion or be involved in collisions than commercial traffic." It is answer D.



I believe I just use the words and answers from the questions to deal with the understanding. So I strongly think that I put no more common sense or "real world" factors which others often claim as the flaw in student's reasoning. With such reasoning, I suggest that this is not a good question.

Answer C indeed helps us to strengthen the conclusion tremendously because the lack of it will make the claim meaningless outright. HOWEVER, even if C true, can the conclusion hold without D? Absolutely NOT! (as my reasoning above)

Assumption is a decisive factor that if it is not there, the conclusion cannot hold, C and D should be both important. One CANNOT say that assumption C appears before assumption D and assumption C bears a heavy weight of an assumption. That would be a ridiculous thing to say because such claim indeed is based on the flow of one's own thinking, whereas we are dealing with the meaning of the possible assumptions themselves in the already claimed conclusion.

there are two conclusions here

If central business districts were restricted to commercial traffic, which includes taxis and buses,(PREMISES)

ASSUMPTION- personal cars are not in the category of commercial traffic ( negate it and the conclusion at below will break

[b]CONCLUSION (1)[/b] most personal cars would not enter urban centers.


ASSUMPTION 2- D.Personal cars are more likely to cause congestion or be involved in collisions than commercial traffic.

MAIN CONCLUSION- Such a reduction in traffic would reduce the risk of congestion and collisions in central business districts.

As James has pointed out correctly, we need to read carefully what has been asked, it is the conclusion in the first line

The conclusion drawn in the first sentence depends on which of the following assumptions?

Here is OE

Identify the Question Type:

The keywords "Depends on…the following assumptions" indicate an Assumption question. In addition, the phrase "drawn in the first sentence" identifies the location of the prediction in question. Don't worry about assumptions pertaining to conclusions drawn elsewhere in the stimulus.

Untangle the Stimulus:

The author predicts in the first sentence that restricting traffic in the urban center to commercial vehicles, including buses and taxis, would eliminate most personal cars from entering the area. The author adds that this would reduce congestion and collisions, but that is not the prediction addressed in the question stem.

Predict the Answer:

In the first sentence, the author predicts that if the urban center were restricted to commercial vehicles only, personal cars would not come in. For this to be true, the author must be assuming that personal cars never function as commercial vehicles.

Evaluate the Choices:

(C) is the best match for the prediction and is the correct answer.

(A) and (B) are irrelevant; nothing in the passage depends on the convenience or design of roads or parking facilities outside urban centers. Neither of these choices has any effect on the prediction that personal cars will not enter the urban center.

(D) presents a fact that pertains to the statement in the second sentence. However, the likelihood of personal cars getting into collisions is not relevant to the first sentence, which is what the question is asking about.

(E) is irrelevant. A possible correlation between commercial and personal vehicles has no impact on the prediction that personal cars will not come into the urban center.

TAKEAWAY: Read the question stem carefully. It may ask about only one part of the stimulus rather than about the entire stimulus.

Negating D does not shatter the argument, as even if personal cars more or less likely to involve in collision , still restricting them to enter urban centers will reduce the congestion and collision.

Answer (C)

The answer is C
The argument proposes a way to reduce the congestion in the Central Business district by restricting traffic to only commercial vehicles .So personal cars would not be allowed to enter the Central Business District .
If people use their personal cars for commercial purpose this will have serious implication the economy of the Central Business District , So C is the necessary assumption.
A and B are unrelated to the argument as we are not concerned about the parking spaces
E is also out as it does not concern present situation

D is actually tricky It gives new information about personal cars to more likely cause congestion or collision but if we negate it still we can reduce the traffic congestion by reducing personal cars as people will be forced to use public transport.

C.Most personal cars are not used for commercial purposes.