Most geologists believe oil results from chemical transformations of

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).


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!


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.


(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.


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.