Critical Reasoning

why no B?

IMO E

Why not B?
For assumption type CR question when you are not sure about the answer try Negating the option you have narrowed down to.

Like here we can clearly discard A (Usage), C (Effectiveness), and D (Evidence Finding)

Now Negate B:
Not all creatures have the network vessel in their skin.

Does it destroy the conclusion "dinosaurs were flapping, not just gliding"?
We know the sole purpose of the Network is to Disperse Heat (See in passage Only because bats...) but does it Mean that Heat Can be Dispersed only via this Network. NO. That can happen in any other way also which is not mentioned in the passage. Thus negating B does not destroy the conclusion.

Option E is correct I believe as it closes the possibility which can make the conclusion weak. The possibility is marked red in above line.

The answer is A.

E is correct on these counts:

The conclusion is that Sandactylus must have flown for it had network of blood vessels in its wings and not that the blood vessels are the ONLY way of dispersing heat!


The evidence is that:

Bats have these blood vessels and these serve only the purpose of dispersing heat

The bats generate this heat only because of flapping.

Now what the argument wants to say is this " There is something called X in bats.This X acts like a coolant in car.The car generates heat when it runs.Since I can see this X in a museum,therefore museum also runs [his logic heat is generated only running and the thing called X was not just a show piece]

Even I go with E . Whats the OA?

OA is A

Deepthi Subbu wrote:Even I go with E . Whats the OA?

Post your reasoning.If you chose E over all choices,why did you eliminate A?

Negate E

" Heat could have been dispersed by something else" lets say its beak

It doe not qualify that the "these blood vessels were useless"

It basically means that there are two or more ways in which heat can be dispersed.So the blood vessels still disperse heat.The only thing that you negated is that "there is no other way"!

For eg : "There a quant question.I say the method that I have used is a way to solve this problem"

If you say that my assumption is "there is no other way of solving this question",your reasoning is flawed.

It's negation gives "There may be other ways of solving this question.But it does NOT prove that my method is INCORRECT"

On the other hand if I say as in A "The bird would not have had these blood vessels in wings if these were of no use"

It's negation becomes "The bird would have had these blood vessels even if they were of NO use"

From this,I just can't conclude that these blood vessels were used for dispersing heat.!

Another example:

Human beings eliminate waste products such as salt from body through large intestine.Since animal X too has large intestine ,it too must be able to remove salts from body through that intestine.

Now you are saying "Salts from the body could not have been excreted through other things such as skin.

Does this disqualify my argument? NO

As a matter of fact,humans TOO remove wastes through other mechanisms such as skin.

You basically just said ONLY large intestine is a way of removing waste! but my conclusion wasn't this!