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Re: Most geologists believe oil results from chemical transformations of [#permalink]
2
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It should be E IMO.

because if both chemical transformation and bacteria are reducing hydrocarbon and complex hydrocarbons respectively to the same amount then obviously oil reserves will be more for the one which is in greater quantity beneath the earth( which is the complex hydrocarbon in this case)
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
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A) Most geologists think optimistically about the Earth's reserves of oil.
weakens the conclusion in a way.

(B) Most geologists have performed accurate chemical analyses on previously discovered oil
reserves.
this doesn't support the conclusion.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.
Not related

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface
contaminants.
weakens the conclusion.

(E) Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.

this shows the possibility of the stated Conclusion so strengthens :)
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
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+1E

Premise 1 - Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas. Suppose instead, that oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth.

Premise 2 - As is well known, the volume of these hydrocarbons exceeds that of buried organisms

Conclusion - Therefore, our oil reserves would be greater than most geologists believe.

If we look at premise 2 , it states that the “volume of the hydrocarbons exceeds that of buried organisms”. I think, if any option ascertains this or add something to the premise, it will be our answer.

Option E clearly states that that change in volume is same for both, (volume of the hydrocarbons exceeds that of buried organisms), (oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth), these imply that the oil reserves are high.

:-D
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
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E is right. We can check by negating E and seeing whether that would weaken the conclusion.
Chemical transformations reduce the volume of buried hydrocarbons derived from organisms in a much greater proportion than bacterial action reduces the volume of other complex hydrocarbons. - This would mean that even though the volume of the hydrocarbons exceeds that of buried organisms, the oil reserves resulting from bacterial action on them might be much lesser.
eg: If 10000000000 Kgs of the hydrocarbons only gives 1 litre of oil this would hardly make any difference
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
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vishy007 wrote:
Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas. Suppose, instead, that oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth. As is well known, the volume of these hydrocarbons exceeds that of buried organisms. Therefore, our oil reserves would be greater than most geologists believe.

Which of the following, if true, gives the strongest support to the argument above about our oil reserves?

(A) Most geologists think optimistically about the Earths reserves of oil.

(B) Most geologists have performed accurate chemical analyses on previously discovered oil reserves.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface contaminants.

(E) Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.


This is a close call between (B) and (E). Our conclusion states that oil reserves would be greater than most geologists believe.
We want to strengthen that claim. Now, first of all. We have that oil reserves > expected.

So for starters, we could use two pieces of evidence to strengthen this relationship.

Let's take a look at B first. We are being told that the current oil reserves are accurate. Therefore if we were to compare them with the new discoveries for bacterial, we could in fact know if the oil reserves would be greater than most scientists believe ONLY IF we could measure the oil reserves from bacterial action accurately, which is not addressed here and this is IMO the thing that makes this answer choice inferior to E.

On the other hand, in E we have that the proportion of oil that could be found from bacterial action measured in volume reduction is similar as that of the buried hydrocarbons. The stimulus already states that there is more volume of complex hydrocarbons than the fossils so given this new piece of information if rates are similar then the oil from this new type of source will be higher. So it is basically saying that there is a good and accurate way to measure these oil reserves. I think this answer choice does a pretty good job in strengthening the argument that oil reserves > expected

So I think E wins this one by a small margin

Hope it helps
Cheers!
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
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vishy007 wrote:
Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas. Suppose, instead, that oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth. As is well known, the volume of these hydrocarbons exceeds that of buried organisms. Therefore, our oil reserves would be greater than most geologists believe.

Which of the following, if true, gives the strongest support to the argument above about our oil reserves?

(A) Most geologists think optimistically about the Earths reserves of oil.

(B) Most geologists have performed accurate chemical analyses on previously discovered oil reserves.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface contaminants.

(E) Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.


CR09461.01


Official Explanation

Argument Evaluation

What new information, if added to the argument, would strengthen it?

The argument sets forth a novel hypothesis about how oil reserves are created. That is, oil reserves are created through bacterial action on complex hydrocarbons within the earth rather than through chemical transformation of hydrocarbons derived from organisms buried under ancient seas.

The argument notes that the volume of the hydrocarbons that bacteria transform to yield oil is greater than the volume of hydrocarbons derived from the buried organisms and concludes that total oil reserves are greater than most geologists believe them to be.

A. This suggests that most geologists might, if anything, be inclined to overestimate oil reserves. However, this consideration has little bearing on the chemical origin of oil or how much oil may remain buried in the earth.

B. This does not tell us whether the chemical analyses can identify whether the oil originated from hydrocarbons derived from buried organisms.

C. The existence of buried ancient seas has little, if any, relevance to the argument. This choice fails to provide evidence that by itself would help decide whether the hypothesized bacterial origin of oil actually supports the inference that oil reserves are greater than is currently assumed.

D. This suggests that bacteria have been found in some oil reserves; the potential importance of this discovery is unclear.

E. Correct. This strengthens the argument: if it is true, then the greater abundance of complex hydrocarbons from which it is hypothesized that oil can be derived through bacterial action would predict much larger oil reserves than exist under most geologists' current predictions.

The correct answer is E.
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
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[quote="vishy007"]Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas. Suppose, instead, that oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth. As is well known, the volume of these hydrocarbons exceeds that of buried organisms. Therefore, our oil reserves would be greater than most geologists believe.

Which of the following, if true, gives the strongest support to the argument above about our oil reserves?

(A) Most geologists think optimistically about the Earths reserves of oil.

(B) Most geologists have performed accurate chemical analyses on previously discovered oil reserves.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface contaminants.

(E) Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.


ANALYSIS
Passage clearly says bacterial action on other complex hydrocarbons (Lets call it B) exceeds (A)chemical transformations of hydrocarbons .

OPT ABD make no sense so they are out .

C Vs E
C is tempting but is wrong once you realise that passage already mentioned B is more than A as it exceeds A . If we choose C then it means we are going against the given facts .

So By POE you can reach to your answer E .
However dont let the word roughly the same proportion get you tempted to reject this option coz roughly the same can be the case if B is 10 and A is 9 (here B exceeds A and at same time is roughly same in proportion ).
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
Hi Experts, Can you explain why E is the answer? I wasn't able to eliminate C.
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
Ujaswin wrote:
Hi Experts, Can you explain why E is the answer? I wasn't able to eliminate C.


Hi

Let us assume (C) to be true and see how it affects our conclusion.

Conclusion: Our oil reserves would be greater than most geologists believe.

Premises on which it is based:

1) Oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth.
2) The volume of these hydrocarbons exceeds that of buried organisms.
3) Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas.

Now consider option (C), which states: Ancient seas are buried within the Earth at many places where fossils are abundant.

How does this impact the conclusion, which pertains to current beliefs held by most geologists about the extent of oil reserves vis-a-vis an alternate possibility? If ancient seas are buried "at many places" with fossils, this does not tell us anything about the present belief on oil reserves vis-a-vis the alternate explanation discussed in (1) above. It is possible for (C) to be true AND oil obtained from other complex hydrocarbons to be more OR less than present extent of oil reserves. Therefore, this option does not impact our conclusion in any way.

Hope this helps.
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
vishy007 wrote:
Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas. Suppose, instead, that oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth. As is well known, the volume of these hydrocarbons exceeds that of buried organisms. Therefore, our oil reserves would be greater than most geologists believe.

Which of the following, if true, gives the strongest support to the argument above about our oil reserves?

(A) Most geologists think optimistically about the Earths reserves of oil.

(B) Most geologists have performed accurate chemical analyses on previously discovered oil reserves.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface contaminants.

(E) Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.


I marked option E as per the same reasons as mentioned by others but couldn't convincingly eliminate C

As per C, more buried ancient seas --> fossils abundant

Is it because there is no mention of fossils in the argument and thus this is irrelevant?
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
ProfChaos wrote:
vishy007 wrote:
Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas. Suppose, instead, that oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth. As is well known, the volume of these hydrocarbons exceeds that of buried organisms. Therefore, our oil reserves would be greater than most geologists believe.

Which of the following, if true, gives the strongest support to the argument above about our oil reserves?

(A) Most geologists think optimistically about the Earths reserves of oil.

(B) Most geologists have performed accurate chemical analyses on previously discovered oil reserves.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface contaminants.

(E) Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.


I marked option E as per the same reasons as mentioned by others but couldn't convincingly eliminate C

As per C, more buried ancient seas --> fossils abundant

Is it because there is no mention of fossils in the argument and thus this is irrelevant?


Hello ProfChaos! Although I am pretty late to the party, I will try to help you out here.

Option C just states that at many places where there is a good number of fossils present, ancient seas are also present at the same location. But this fact does not help in anyway to strengthen the conclusion that "our oil reserves would be greater than most geologists believe."

Straightaway go to option E and you can find that this options helps in strengthening our conclusion. :)
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas. Suppose, instead, that oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth. As is well known, the volume of these hydrocarbons exceeds that of buried organisms. Therefore, our oil reserves would be greater than most geologists believe.

Which of the following, if true, gives the strongest support to the argument above about our oil reserves?


Qtype: Strengthen
POA:
Find conclusion
Read premise again
Go through answer options and remove answers not related to the conclusion (Out of scope, OS)
Check remaining options and compare


MOST Geologists believe oil comes from chemical transformation of HCs from organisms buried under ANCIENT SEAS.
Hypothetically: If oil comes from bacterial action on other HCs which are trapped WITHIN EARTH.
Fact: Hydrocarbons trapped are more than HCs that come from organisms.
Conclusion: Our oil reserves will be greater

The author believes that if we could use bacterial action(a different process than standard) on HCs trapped within earth (qty of HCs is even more than what we get from ancient seas) we will have more oil reserves than what MOST geologists believe we have presently.


Let's look at answer options and remove OS.

(A) Most geologists think optimistically about the Earths reserves of oil.
This is not related to our conclusion. OS. - Remove

(B) Most geologists have performed accurate chemical analyses on previously discovered oil reserves.
Not related to our conclusion. We want to prove that we will have more oil reserves than what is currently assumed.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.
This is a confusing statement, but since it talks about points relevant to our passage. let's keep it for now.

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface contaminants.
This is OS. We don't care about how current bacteria reached oil reserves. We want to prove that we will have more yield if the hypothetical situation were true.

(E) Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.

This is interesting, it weakens a weakener.
Since we were comparing two different processes, it becomes easy to weaken one process over the other by simply suggesting that the other process would not yield similar output.
e.g. if someone were to say that Bacterial processes completely destroy hydrocarbons, then that would weaken the conclusion.

Rule in CR is weakener of a weakener is a strengthener (enemy of an enemy is a friend). Hence, this answer is a strengthener.

Let's look at the other option we had kept.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.
This statement just states that the ancient seas, which have HCs from organisms, are within Earth.

This sounds like OS to me since we were comparing other HCs from HCs from organisms. And the quantity of other HCs has already been mentioned as more than what we get from seas.

Hence, E should be the answer
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
vishy007 wrote:
Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas. Suppose, instead, that oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth. As is well known, the volume of these hydrocarbons exceeds that of buried organisms. Therefore, our oil reserves would be greater than most geologists believe.

Which of the following, if true, gives the strongest support to the argument above about our oil reserves?

(A) Most geologists think optimistically about the Earths reserves of oil.

(B) Most geologists have performed accurate chemical analyses on previously discovered oil reserves.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface contaminants.

(E) Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.


CR09461.01


Conclusion: our oil reserves would be greater than most geologists believe.

Given: As is well known, the volume of these hydrocarbons exceeds that of buried organisms.

which means, if there's \(100 m^3\) of volume of buried organisms, then there should exist \(>100 m^3\) of complex hydrocarbons.

E says, Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.

that means, the proportion of in which they both reduce is roughly same. lets take 50%? so doing that, we get 50m^3 oil from buried organisms and > 50 m^3 from complex hydrocarbons..

Is my line of thinking correct ? Please help MartyTargetTestPrep KarishmaB AndrewN GMATNinja ScottTargetTestPrep
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
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lostminer wrote:
vishy007 wrote:
Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas. Suppose, instead, that oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth. As is well known, the volume of these hydrocarbons exceeds that of buried organisms. Therefore, our oil reserves would be greater than most geologists believe.

Which of the following, if true, gives the strongest support to the argument above about our oil reserves?

(A) Most geologists think optimistically about the Earths reserves of oil.

(B) Most geologists have performed accurate chemical analyses on previously discovered oil reserves.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface contaminants.

(E) Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.


CR09461.01


Conclusion: our oil reserves would be greater than most geologists believe.

Given: As is well known, the volume of these hydrocarbons exceeds that of buried organisms.

which means, if there's \(100 m^3\) of volume of buried organisms, then there should exist \(>100 m^3\) of complex hydrocarbons.

E says, Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.

that means, the proportion of in which they both reduce is roughly same. lets take 50%? so doing that, we get 50m^3 oil from buried organisms and > 50 m^3 from complex hydrocarbons..

Is my line of thinking correct ? Please help MartyTargetTestPrep KarishmaB AndrewN GMATNinja ScottTargetTestPrep

Yes, lostminer, you have assessed answer choice (E) correctly. Well done.

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Re: Most geologists believe oil results from chemical transformations of [#permalink]
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vishy007 wrote:
Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas. Suppose, instead, that oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth. As is well known, the volume of these hydrocarbons exceeds that of buried organisms. Therefore, our oil reserves would be greater than most geologists believe.

Which of the following, if true, gives the strongest support to the argument above about our oil reserves?

(A) Most geologists think optimistically about the Earths reserves of oil.

(B) Most geologists have performed accurate chemical analyses on previously discovered oil reserves.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface contaminants.

(E) Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.


CR09461.01


Geologists - Oil forms from chemical transformations of hydrocarbons derived from organisms buried under ancient seas.
Hypothesis - Oil actually forms from bacterial action on other complex hydrocarbons that are trapped within the Earth.
Volume of complex hydrocarbons > volume of buried organisms.

Conclusion: Our oil reserves would be greater than most geologists believe.

What the argument tells us is that geologists believe that organisms are the raw material for oil. But what if complex hydrocarbons are the raw material? Since complex hydrocarbons are more in volume, our oil reserves could be more than what geologists believe. But hey, just because more raw material is available, we can't say that we will get more end product. What if the different processes used to covert raw material to end product in the two cases lead to using more raw material for the same or even less quantity of end product? Then we cannot conclude that end product in case the hypothesis is correct will be more.
(E) tells us that both processes reduce their respective the raw materials by the same percentage to give the end product. Then, higher volume of raw material will mean higher volume of end product. This does make our conclusion more likely.

Let's look at the other options too.

(A) Most geologists think optimistically about the Earths reserves of oil.

Our conclusion is: Our oil reserves would be greater than most geologists believe.
If the truth is that geologists are optimistic about our oil reserves, it means that actual oil reserves are lower than what geologists believe. Then our conclusion weakens. It certainly doesn't strengthen

(B) Most geologists have performed accurate chemical analyses on previously discovered oil reserves.

If geologists have performed accurate chemical analysis, it is likely that they know the actual raw material. Then the geologists may be correct in their assessment and oil reserves may be as per their assessment. Again, if anything, this option casts doubt on our conclusion and certainly doesn't strengthen it.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.

Irrelevant

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface contaminants.

If it seems that we are the ones who introduced the bacteria in oil reserves, it makes the hypothesis unlikely. Hence our conclusion weakens instead of strengthening.

Answer (E)
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
GMATIntensive wrote:
The Story

Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas. - The author states the belief of most geologists (you’ll observe that whenever the author presents a belief of another party, the chances are high that the author is going to oppose the belief). The belief is that oil results from some changes in the chemical structures of certain hydrocarbons. Which hydrocarbons? Those derived from certain organisms. Which organisms? That are buried under ancient seas.

Suppose, instead, that oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth. - The author supposes a scenario. ‘Instead’ indicates that it’s going to be in the opposite direction to the previous statement. The scenario is that oil results when bacteria acts on other complex hydrocarbons. Not the hydrocarbons mentioned in the first statement. Which hydrocarbons then? That are trapped within the Earth. So, this is a different way of formation of oil from the one believed by the geologists. Basically the author supposes that oil is formed a different way and not the way most geologists believe.

As is well known, the volume of these hydrocarbons exceeds that of buried organisms. - It is well known that these hydrocarbons (mentioned in the second statement) are much greater in volume than the buried organisms (mentioned in the first statement).

Therefore, our oil reserves would be greater than most geologists believe. - On the basis of the previous statements, the author arrives at a conclusion that our oil reserves would be greater than most geologists believe. Why greater? Because the source of oil could be these hydrocarbons trapped within the Earth that are much greater in volume.

Gist:
Most geologists believe that oil originates from buried organisms. However, oil could result from hydrocarbons trapped within the earth. If that were the case, since the volume of these hydrocarbons exceeds the volume of buried organisms(support), our oil reserves would be greater than most geologists believe(conclusion).

The Gap

It’s an interesting argument since the entire logic hinges on the initial supposition. One easy way to challenge the argument would be to challenge the supposition – to present evidence that calls the supposition into question.

The second gap in the argument is the jump from the volume of the source (hydrocarbons) to the volume of oil. Just because there is a huge volume of these hydrocarbons, can we be sure that there is a corresponding huge volume of oil? Nope. What if there is only very limited bacteria out there that can convert these hydrocarbons into oil? Also, what if only a small proportion of these hydrocarbons can be converted into oil? What if the oil generated from bacterial actions on these hydrocarbons chemically transforms into something non-oil over time? Also, what if the volume of hydrocarbons generated from the buried organisms turns out to be much greater than the volume of the buried organisms?

The third gap in the argument is that the argument assumes that the geologists’ belief about the current levels of oil is based on their understanding of how oil is formed. It is entirely possible that

There are quite a few gaps here!

The Goal

We have to find an option that gives the strongest support to the author’s conclusion that our oil reserves would be greater than most geologists believe. We can strengthen the conclusion by strengthening any of the gaps mentioned above. Of course, there could be other gaps as well.

The Evaluation

(A) Most geologists think optimistically about the Earths reserves of oil.
Incorrect. Thinking optimistically indicates overestimation. If their belief of the reserves of oil is an overestimation, doesn’t that slightly reduce the belief that the actual reserves would be greater than the geologists believe? What if they believe that there are 10 times the reserves there currently are? In such a case, even if we get into our supposed situation, it seems unlikely that the actual oil reserves would be greater than geologists believe. So, this option is in a negative (weakening) direction while we are looking for a strengthener.

(B) Most geologists have performed accurate chemical analyses on previously discovered oil reserves.
Incorrect. This option too is in a negative direction. If the geologists have performed accurate chemical analyses, probably they are right about the formation of oil, and thus the author’s supposition is probably wrong.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.
Incorrect. This option indicates that ancient seas are a good source of fossils (or buried animals). So what? The entire argument stands as is. The volume of hydrocarbons trapped within the earth still is larger than the volume of these buried animals.

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface contaminants.
Incorrect. This option too is in a negative direction. If the ‘only’ bacteria found in oil reserves probably came from the surface, the suggestion is that there is no bacteria down there inside the earth in these oil reserves. Thus, our supposition that oil forms from bacterial action on complex hydrocarbons seems a bit unlikely.

(E) Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.
Correct. This option strengthens the argument by eliminating a potential weakener. Here’s that weakener: chemical transformations reduce the volume of buried hydrocarbons significantly less than bacterial action reduces the volume of other complex hydrocarbons. In such a case, even though we have a higher amount of these other complex hydrocarbons, we won’t be sure that we’d have a higher volume of oil as well since bacterial action significantly reduces the volume of these complex hydrocarbons. Let’s take these numbers to understand:

Volume of buried hydrocarbons derived from organisms, x = 10

Volume of other complex hydrocarbons, y = 30.

Chemical transformation reduces x to 7 while bacterial action reduces y to 6. In such a case, we’ll rather have less oil from bacterial action on complex hydrocarbons.

Additional Notes

As you may have observed, three out of the four incorrect options are in the negative direction. So, they can be easily eliminated by just considering that they are indicating something opposite of what we are looking for. In the exam time, we need not worry about the magnitude of the impact of such options since the sign (or direction) is wrong. This is our common practice that whenever we evaluate an option, we first pay attention to the direction of the option. If the option is in the opposite direction, we need not pay attention to how much its impact is. We have seen many people wasting a lot of time on options that seem very close to them but are actually in the opposite direction.

SC Notes:
The sentence “our oil reserves would be greater than most geologists believe” is noteworthy for the way the comparison is presented. Ideally, the comparison should have been presented in this way: “our oil reserves would be greater than what most geologists believe they are”. We believe that the given sentence is also a correct way of presenting the comparison.

If you have any doubts regarding any part of this solution, please feel free to ask.


Hi GMATIntensive! I found one of the sentences to be cut off mid-way. Could you please complete it so that we could understand the third logic gap? My OCD is nagging me here :)

The particular sentence - The third gap in the argument is that the argument assumes that the geologists’ belief about the current levels of oil is based on their understanding of how oil is formed. It is entirely possible that
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
[quote="vishy007"]Most geologists believe oil results from chemical transformations of hydrocarbons derived from organisms buried under ancient seas. Suppose, instead, that oil actually results from bacterial action on other complex hydrocarbons that are trapped within the Earth. As is well known, the volume of these hydrocarbons exceeds that of buried organisms. Therefore, our oil reserves would be greater than most geologists believe.

Which of the following, if true, gives the strongest support to the argument above about our oil reserves?

(A) Most geologists think optimistically about the Earths reserves of oil.

(B) Most geologists have performed accurate chemical analyses on previously discovered oil reserves.

(C) Ancient seas are buried within the Earth at many places where fossils are abundant.

(D) The only bacteria yet found in oil reserves could have leaked down drill holes from surface contaminants.

(E) Chemical transformations reduce the volume of buried hydrocarbons derived from organisms by roughly the same proportion as bacterial action reduces the volume of other complex hydrocarbons.


We know from the passage that "the volume of these hydrocarbons (from complex hydrocarbons trapped in earth) exceeds that of buried organisms (buried under ancient seas)".
One way the amount of oil reserves from earth hydrocarbons would be greater is if the processes that are used to convert the fossils into oil in this case would not greatly reduce the volume of hydrocarbons it can utilise for oil. In simple terms, if the bacteria eats a lot of the fossil to make a certain amount of oil and in comparison, the chemical transformation of buried fossils consumes very less of the fossil to produce same amount of oil (saying chemical transformation is more efficient than bacteria action) then even lesser amount of fossils buried can produce more oil. We need to tackle this scenario to strengthen the conclusion. If volume of earth fossils > buried fossils (as is given) then according to option E, both processes (bacteria action and chemical transformation) equally use up fossils to create equal amount of oil. So this factor remaining the same higher volume of earth fossils should produce more oil than lower volume of sea fossil. Thus strengthening the claim that oil reserves would be greater than what geologists believe (what they believe is that oil source is the sea fossils).
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Re: Most geologists believe oil results from chemical transformations of [#permalink]
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