The postal service is badly mismanaged. Forty years ago, first-class

I agree with E.

E can strengthen or weaken. We cant say that it weakens for sure. Notice that "average level of consumer prices" have increased. We don't know whether 'postal service' prices specifically increased or decreased. If it increased then it weakens the argument, if it decreased then it strengthens the argument.

C definitely weakens the argument because it specifically mentions that for "comparable delivery charges" others charge more.

The argument says that the "postal service" prices has also increased. This is evident in line "Forty years ago, first-class letter delivery cost only three cents. Since then, the price has increased nearly tenfold,"
But the problem is that, the increase in postal service prices are at a much higher rate than the increase in average consumer prices.

Agreed. thanks for pointing !! But somehow I could smell the wrong answer choice with some keywords

OA is E.

I found the OA in the answer key download for CR1000 (reference: Test D qn 7).
It would really be nice if original poster could post up OA together with the questions each time...

I chose C initially.

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I figured this is how it should be -
Conclusion: postal service badly managed.
Premise: increased price by 10x; decreased efficiency and reliability

Answer should strengthen this.

A - weakens. Gives postal service an excuse to say it's not their fault for increased price n decreased efficiency/reliability
B - weakens. again, not postal services' fault! It was circumstantial.
C - weakens. Over here, it tells us, hey...comparatively, postal service charges less --> good management!
D - weakens. Increased efficiency! --> good management!
E - strengthens. Across the board, consumer prices increased only 3-folds. Postal service increased 10x!! Mismanagement!!

I think it is important to understand here whether to Strengthen or Weaken the Conclusion.
Conclusion: The postal service is badly mismanaged
Weaken: Not Mismanaged
Except: It is mismanaged.

E does the job. Rest all weakens the mismanagement claim.

First of all always post the OA once the question is posted.

IMO the answer is "C".
The answer would have been more clear if the words in the premise were twofold rather than tenfold. And I'll tell you why.

(A) The volume of mail handled by the postal service has increased dramatically over the last forty years.
Weakens. Because the volume of the mails has increased to such an extent that postal services cannot be blamed for the mismanagement.

(B) Unprecedented increases in the cost of fuel for trucks and planes have put severe upward pressures on postal delivery costs.
Weakens. Because cost is some other reason explaining why the postal services cannot be claimed as mismanaged.

(C) Private delivery services usually charge more than does the postal service for comparable delivery charges.
Irrelevant. Because no comparison of delivery charges between Private and Postal services justifies the mismanagement of Postal services. It could be that Private delivery charges were greater forty years ago. Also, the word 'usually' suggests uncertainty. Thus this option could be our possible answer. But, lets go through other options as well.

(D) The average delivery time for a first-class letter four decades ago was actually slightly longer than it is today.
Weakens. Because the timings of certain type of delivery was longer than what is it now. So slightly weaken the premise, but weakens.

(E) The average level of consumer prices overall has increased more than 300 percent over the last forty years.
Weakens. Because average level of consumer price increased more than 4 times(300% over the original value) in last forty years. Whereas the premise of the argument states that the price of postal services increased nearly tenfold(ten times). So the crucial word here is 'more than'. It could mean that increase in consumer price is either 1)<(less than tenfold) or 2) =(equal to tenfold) or 3) > (greater than tenfold). In the second and third cases the option could support the argument whereas in the first case the option is clearly weakening the argument. So the argument is partly Weakened.

So Clearly, the best answer choice we are left with is 'C'.

P.S. This question is not very clear in meaning and its lack a proper framework. In Fact it is from the group of questions that aren't good enough to be tagged as GMAT level question. In here we have to chose the best option among the worst.

The postal service is badly mismanaged. Forty years ago, first-class letter delivery cost only three cents. Since then, the price has increased nearly tenfold, with an actual decrease in the speed and reliability of service.
Each of the following statements, if true, would tend to weaken the argument above EXCEPT:

(A) The volume of mail handled by the postal service has increased dramatically over the last forty years. - Wrong
This choice Weakens the conclusion by saying Mismanagement is due to the dramatic increase in the volume of mails.

(B) Unprecedented increases in the cost of fuel for trucks and planes have put severe upward pressures on postal delivery costs. - Wrong
This choice Weakens the conclusion by saying Transportation costs are the real reason for mismanagement.

(C) Private delivery services usually charge more than does the postal service for comparable delivery charges. - Wrong
If the Private delivery services are more costly then mismanagement is due to some other reason in the postal service.

(D) The average delivery time for a first-class letter four decades ago was actually slightly longer than it is today. - Wrong
Delivery time decades ago was not very very less compared to today's delivery time.

(E) The average level of consumer prices overall has increased more than 300 percent over the last forty years. - Correct
This supports clearly the conclusion saying, prices have increased leaps and bounds and still the service is poor.

We need to find the answer which does not weaken the argument given.
The argument given is 'Postal service is mismanaged.Why? Because apparently the cost has increased after 40 years and service is not that reliable'
Now how can we weaken this argument? We can weaken it by pointing out an increase the postal service workload.
Now as the volume has increased dramatically, postal service workload has increased dramatically so automatically cost will increase, service can be delayed because of this excess workload. So, it does not mean Postal service is mismanaged. Thus it weakens the argument.

I hope it clears. Sorry if it wasnt precise or concise explanation.

Hello expert,
I agree E can weaken, but I think C is irrelevant, though doesn’t weaken. Whether the price of Private delivery is higher or lower is irrelevant to the management level of postal service. I mean, [the competitors are bad] is irrelevant to [postal service is good].
Since the question is to seek a weakener, so I think C and E are both correct. Pls shed some light, thanks.

Exactly as what I wanna say.
C is actually irrelevant, we are talking about whether the postal service is badly mismanaged, whether private delivery services charge more or less than the postal service has nothing to do with the conclusion. They are not the same thing, as you can't compare AI industry with consumer goods industry. They may have huge difference (you can't simply assume they are the same without any specific mention in the information presented, as is one principle in GMAT), which means the charge difference between those two industries can't be used to determine whether one of them is mischarged.
While on the other hand, the expression "[color=#ff0000]more than" in E could be much more than tenfold, and I think this is actually an very important point which you should pay great attention in the GMAT exam.[/color]