Critical Reasoning

Please refer to the image . Need explanation to the option A please.

And what if we have an answer choice like this :

Of the various types of radiotion blocked by ozone, UV-B is NOT the only type that can damage genes.

Will it stregthen the argument ? Please explain.. I gt a bit confused on this.

Edited the post to include 'NOT' in the choice I have made up.

A is extreme, it says UV radiation ONLY is responsible but we may guess cosimic radiation may also modify the nature of skin.

IMO A strengthens the argument.

The argument says that amphibians are decreasing in population because of the genetic defect caused by UV-B rays, a type of radiation from sun. Moreover, it also says that depletion of ozone layer has caused the harmful radiations, one of them being UV-B, to reach earth.

Option A says, among those radiations only UV-B is harmful.

Reason 1:
Thus, it states that even though the other type of radiations are harmful irrespective of they being blocked by ozone or not. Thus, A strengthens.

Reason 2:
Since the argument talks only about one kind of UV rays, we are not bothered about the other type of UV rays.

IMO D.

Please correct me incase I am wrong.

IMO A strengthens the argument.

The argument says that amphibians are decreasing in population because of the genetic defect caused by UV-B rays, a type of radiation from sun. Moreover, it also says that depletion of ozone layer has caused the harmful radiations, one of them being UV-B, to reach earth.

Option A says, among those radiations only UV-B is harmful.

Reason 1:
Thus, it states that even though the other type of radiations are harmful irrespective of they being blocked by ozone or not. Thus, A strengthens.

Reason 2:
Since the argument talks only about one kind of UV rays, we are not bothered about the other type of UV rays.

IMO D.

Please correct me incase I am wrong.

Sorry for cluttering the thread by posting the reply twice.

Is somehow got posted twice accidentally or may be due some uncertain behaviour of IE in my PC.

Can someone help me with how to delete the duplicate post?

bubbliiiiiiii wrote:Sorry for cluttering the thread by posting the reply twice.

Is somehow got posted twice accidentally or may be due some uncertain behaviour of IE in my PC.

Can someone help me with how to delete the duplicate post?

Consider this forum yours.
A) says that the only radiation that damages genes is UV-B against which the ambhibian pop. has not been armed with any protection.If there was other radiation that was responsible for damage to genes, we dont know whether the amphibian population was at a disadvantage as far as protection is concerned or at an advantage with respect to others.

+1 for A.

I find it hard to believe that this is a good representation of anything that we would see in the test. I came to A by POE, but I cant really come up with a great reason for it.

1. Amphibian population is decreasing and at the same time ozoze is depleting
2. Ozone blocks UVB, which can damage genes
3. Amphibians dont have natural protection from UVB
4. Loss of ozone is responsible for the loss of amphibians

Working backwards:

E. Incorrect. This provides evidence of sorts that the population decline has gone hand in hand with the time frame that the ozone has depleted.

D. Incorrect. This gives us the knowledge that there are not other factors about their natural habitat that are causing them to die

C. Incorrect. This adds more evidence that the ozone is related to amphibian population

B. Incorrect. This shows that species with UV protection are not being damaged as much as those without the UV

A. Correct. This doesnt really add any evidence to the argument. We are concerned with ozone depletion and this only tells us that UV-B damages genes which we already knew from the initial passage.

@fitzgerald23 : Thanks a lot. Your explanation is to the point. Source is PowerPrep GMAT Bible.

Question: What if choice A is worded like this :

Of the various types of radiotion blocked by ozone, UV-B is NOT the only type that can damage genes.

What impact it will have on the argument ?

Could someone give it a try please

Question: What if choice A is worded like this:
Of the various types of radiotion blocked by ozone, UV-B is NOT the only type that can damage genes.
What impact it will have on the argument ?

GMATMadeEasy wrote:Could someone give it a try please

Question: What if choice A is worded like this:
Of the various types of radiotion blocked by ozone, UV-B is NOT the only type that can damage genes.
What impact it will have on the argument ?

I still do not think that it will change the fact that A is not really adding any information to the argument. Remember the argument is that ozone is the problem not UV-B. UV-B is one of the types of radiation that is let through by the ozone but not the only one.

GMATMadeEasy wrote:Could someone give it a try please

Question: What if choice A is worded like this:
Of the various types of radiotion blocked by ozone, UV-B is NOT the only type that can damage genes.
What impact it will have on the argument ?

Irrelevant to the argument .

A strengthen correct answer will always have a positive effect on the conclusion of the argument. So identifying the conclusion should be the first thing that you do.

In this case the conclusion is a causal one and illustrates the connection between the ozone layer depletion and the decline of the amphibian population.

c: the depletion of the ozone layer causes the decline of the amphibian population

Since this is a strengthenX question, the answer will do the opposite of what a normal strengthen answer will do. That is to say it will not strengthen the argument (which does NOT mean that it will weaken the argument)

(A) says that UV-B is the only type of non-blocked radiation that can damage genes. It is irrelevant to the argument. Since the scope of the argument is already the unblocked UV-B rays this literally does nothing.

@fitzgerald23: thanks a lot