Critical Reasoning

tropical forests produce a large percentage of the earth's supply of oxygen. continued destruction of these forests is likely to reduce the earth's oxygen supply to levels that will threaten the existence of all oxygen-dependent life on earth.

which of the following, if true, most seriously weakens the prediction above?

A) all of the oxygen produced by the earth's tropical forests is consumed by bacteria and animals living in those forests.
B) some of the oxygen produced by the earth's tropical forests escapes through the upper atmosphere without being consumed.
C) the oxygen produced by tropical forests is consumed by animals all over the earth.
D) the earth's tropical forests are being destroyed at a rate of hundreds of acres everyday.
E) tropical forests contain the most diverse selection of oxygen-dependent animals on earth.

I got it wrong.

IMO A.

Why???Explain please

abhigang wrote:IMO A.

IMO A

argument is saying that 'it will create he threat for ALL oxygen dependent animals"

reply2spg wrote:Why???Explain please

abhigang wrote:IMO A.

Conclusion : The existence of oxygen dependant animals is threatened.
Premise : The oxygen level will get reduced by destruction of forests.

Assumption : Currently, there is a dependence of animals on earth on oxygen from these forest.

A breaks this assumption totally stating that whatever oxygen is produced is used in that forest. Hence other animals are anyway threatend or in other words independant of this oxygen.

B is close. but I had eliminated it because it says SOME gets escaped but still there is some which is used here on erth. Thus the dependancy is not totally broken..

Good one thanks. Yes, oa is A

abhigang wrote:

reply2spg wrote:Why???Explain please

abhigang wrote:IMO A.

Conclusion : The existence of oxygen dependant animals is threatened.
Premise : The oxygen level will get reduced by destruction of forests.

Assumption : Currently, there is a dependence of animals on earth on oxygen from these forest.

A breaks this assumption totally stating that whatever oxygen is produced is used in that forest. Hence other animals are anyway threatend or in other words independant of this oxygen.

B is close. but I had eliminated it because it says SOME gets escaped but still there is some which is used here on erth. Thus the dependancy is not totally broken..

reply2spg wrote:tropical forests produce a large percentage of the earth's supply of oxygen. continued destruction of these forests is likely to reduce the earth's oxygen supply to levels that will threaten the existence of all oxygen-dependent life on earth.

which of the following, if true, most seriously weakens the prediction above?

A) all of the oxygen produced by the earth's tropical forests is consumed by bacteria and animals living in those forests.
B) some of the oxygen produced by the earth's tropical forests escapes through the upper atmosphere without being consumed.
C) the oxygen produced by tropical forests is consumed by animals all over the earth.
D) the earth's tropical forests are being destroyed at a rate of hundreds of acres everyday.
E) tropical forests contain the most diverse selection of oxygen-dependent animals on earth.

I got it wrong.

A via poe, what did u pick btw?

reply2spg wrote:tropical forests produce a large percentage of the earth's supply of oxygen. continued destruction of these forests is likely to reduce the earth's oxygen supply to levels that will threaten the existence of all oxygen-dependent life on earth.

which of the following, if true, most seriously weakens the prediction above?

A) all of the oxygen produced by the earth's tropical forests is consumed by bacteria and animals living in those forests.
B) some of the oxygen produced by the earth's tropical forests escapes through the upper atmosphere without being consumed.
C) the oxygen produced by tropical forests is consumed by animals all over the earth.
D) the earth's tropical forests are being destroyed at a rate of hundreds of acres everyday.
E) tropical forests contain the most diverse selection of oxygen-dependent animals on earth.

I got it wrong.

my answer is also A for this argument. E and D are out of scope, C seems to strengthen the argument . B is close but i dislike the word " some" it uses thus A is my answer

I got confused and got very bad selection as E.

arora007 wrote:what did u pick btw?

For me, it was a straight A.

let me know if anyway I can hep you guys.

Thanks for your offer. I will definitely need help, I don't know why I always think out of the box and do not stick to the scope.

I am working on it, not again 3rd time

paes wrote:For me, it was a straight A. let me know if anyway I can hep you guys.

reply2spg,

I will explain it.
But lets go with your thought process only.

first write(identify) the conclusion and premise of the argument
then I will explain it further.

Thanks for your help Paes.

Conclusion - Reduced Oxygen supply levels will threaten the existence of all oxygen-dependent life on earth.

Premise - tropical forests produce a large percentage of the earth's supply of oxygen.
Continued destruction of these forests is likely to reduce the earth's oxygen supply to reduced level.

When I read passage I felt it is straight forward. However, when I see the options I felt each option is OOS option.

paes wrote:reply2spg,

I will explain it.
But lets go with your thought process only.

first write(identify) the conclusion and premise of the argument
then I will explain it further.

great.
you have identified the conclusion and premises part correctly.
It solves 50% of the part.

Now see, the keyword in conclusion is :

"... the existence of all oxygen-dependent life on earth. "

But A says :

all of the oxygen produced by the earth's tropical forests is consumed by bacteria and animals living in those forests.

Because all of the produced oxygen is consumed inside the forest only.
So only the bacteria/animals living in the tropical forest can get effected.


Now see the conclusion which says that "all O2 dependent life on earth"

Clearly A is weakening the argument.

Actually in this problem, there is no need even to go for B, C D or E

Now read the other choices and let me know which one you find the contender.

Thanks Paes, I got it now.

Only A looks good.

paes wrote:great.
you have identified the conclusion and premises part correctly.
It solves 50% of the part.

Now see, the keyword in conclusion is :

"... the existence of all oxygen-dependent life on earth. "

But A says :

all of the oxygen produced by the earth's tropical forests is consumed by bacteria and animals living in those forests.

Because all of the produced oxygen is consumed inside the forest only.
So only the bacteria/animals living in the tropical forest can get effected.


Now see the conclusion which says that "all O2 dependent life on earth"

Clearly A is weakening the argument.

Actually in this problem, there is no need even to go for B, C D or E

Now read the other choices and let me know which one you find the contender.