More airplane accidents are caused by pilot error than any other singl

You can't. Simply becasue is a really bad question.

It is completely without a logic flowing.

regards

remember that "provides the most support" means just that: the most support. if all four of the other answer choices provide zero support, then a fifth answer choice that bolsters the argument at all, no matter by how little, wins by default.

choice (c) isn't perfect, but it's definitely the best of the five choices.

A) Recently, more pilots have been volunteering for the immunization shots
More pilots have enrolled, implies lots of those pilots that fall under both categories may have also registered and the govt saw a potential threat in this Maybe
B) All commercial airline flights are piloted by two co-pilots, whereas military flights are usually piloted by only one
Sounds like the govt. does not really care about millitary pilots but does care about commercial ones and as he is assisted by two co pilots the safety seems to be not compromised
C) Chemical warfare is likely to escalate in the future
So what ?
D) Military pilots are choosing to resign rather than obtain the immunization shots
It is not necessarly due to the fact that they have to fly commercial aircrafts. Maybe they do not want to compromise their own safety on board a millitary jet
E) Recently, the number of military pilots also piloting commercial airliners has declined
It has declined due to unsaid reasons

Option C says that chemical warfare is likely to escalate in the future. And even though chemical warfare is likely in the future, the military has stopped requiring its pilots to obtain immunization shots against chemical warfare agents. There has to be only one reason behind military's decision and that is - they don't want their pilots to make errors while flying commercial passenger airlines. It's given in the passage that immunization shots are known to cause unpredictable dizzy spells, which can result in pilot error.

If option D is correct then the reason behind the military's decision to abandon immunization shots has to be their desire to stop pilots from resigning, not to reduce the number of commercial airline accidents as it is mentioned in the passage.

Option C is basically highlighting the importance of that agent for pilots and thereby strengthening the claim that the purpose of military's decision is to reduce the jumber of commercial airlines accidents.Even thought the agents are important for pilots because chemical warfare is going to increase in number in future,the military decided to do away with them because (perhaps)it prioritized reduction of no. of accidents.

Posted from my mobile device

I see nothing Bad in it...It is clearly C..Can you point out as to where the flow is missing

Agree with you .. Looks like people are skewing their reasoning to make it tally with OA ,one way or the other.

Yes, agreed. I was working through the book 2013 Peterson's Master the GMAT (bought from Barnes & Noble!) when I posted this. It probably does more harm than good and based on my experience it is not relevant to GMAT CR in the least.

Avoid the aforementioned book.

For those who are interested, here is the OE:

Narrowed down to A and C.
A destroys conclusion.hence C

I don't think this is the best question, but I think the explanation for C is as follows:

IF:Chemical warfare is likely to escalate in the future
AND: The military is dropping the requirement of a measure that blocks the effect of chemical warfare agents on military pilots

THEN: It must be doing so for some reason(s) other than to reduce the effects of those agents on military pilots. One of those reasons may or may not be to reduce commercial airline accidents.

Not very strong support for the conclusion, but none of the other choices provide any support at all. Choice D actually provides evidence against the conclusion.

More airplane accidents are caused by pilot error than any other single factor. The military recently stopped requiring pilots to obtain immunization shots against chemical warfare agents. The shots are known to cause unpredictable dizzy spells, which can result in pilot error. Since many military pilots also pilot commercial passenger airlines, the reason for the military's decision must have been to reduce the number of commercial airline accidents.

Which of the following, if true, provides most support for the conclusion drawn above?

A) Recently, more pilots have been volunteering for the immunization shots
B) All commercial airline flights are piloted by two co-pilots, whereas military flights are usually piloted by only one
C) Chemical warfare is likely to escalate in the future
D) Military pilots are choosing to resign rather than obtain the immunization shots
E) Recently, the number of military pilots also piloting commercial airliners has declined

Is not A better than C ? For C we must assume that the prediction of chemical warfare likely to escalate in the future will cause panic among pilots and hence increase the number of pilots taking the immune shots

But in A), its directly mentioned that more pilots are volunteering to take the shot (for whatever reasons, whether chemical warfare or general safety)

Can someone please shed some light on this?

Neither A nor C supports the conclusion.

The conclusion is:

Military wants to reduce the number of commercial plane accidents, HENCE it is withdrawing the requirement of mandatory immunization.

The correct option should support this CAUSAL RELATION. It does not matter whether more pilots want to immunize themselves, now or in future - this is irrelevant altogether.

(Moreover if the pilots themselves want to take immunization, they are not stopped from doing so - the passage just states that they are not compelled to take the immunization. Nonetheless this has nothing to do with the CAUSAL RELATION stated in the conclusion. )

This question does not seem to be of good quality.

Can anyone explain how negating the option works for D.

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