I get C.

Life can exist without sunlight (which is only visible on the surface).

Example of life in bedrock (not on surface)

Example of life on ocean floor (not on surface)

Therefore:

Surveying the surface to determine if a planet contains life is insufficient.

Should be 'C'.

As the microbial life is under the sea, we can't say by surveying the planet's surface that there is no life.

C...you just cant tell from the surface if life exists on a planet..

Clear C.

A. Don't know anything about volcanic vents
B. Don't know anything about molten center of Earth
C. Correct -- Bacteria has been found well below the surface of the Earth
D. Probably is too strong -- Passage gives no sense of probability
E. The bacteria itself does not need direct sunlight but could be feeding on sunlight-produced substances that trickled down from the Earth's surface

IMO C)

The para clearly states that life can exist in ocean beds and other places so scanning just surface will not ensure whether life exists or not

My take: E

Conclusion is " Not all life depends on energy from sunlight" and as per Powerscore Bible, the answer to this question should be related to the conclusion.
Option E, clearly supports that bacteria's have been found in coal and oil and do not require energy from sunlight...

Please correct me if i am wrong...

OA:C (as per OG11)

Initially I chose (E).However, I was mislead to the answer as choice (C) clearly states that just surveying the surface for existence of life is wrong.Nevertheless, option (C) indirectly states the conclusion that is mentioned in the first line of the given passage.

(C). Some life exists even under the surface => Just surveying surface won't do=> Not all life depends on energy from sunlight.

Hope it helps

Rgds,
TGC !!

E strengthens the argument. Conclusion should either summarize what is stated in the premises or use the premises as facts to prove a point. E serves as an evidence to support the fact "Not all life depends on energy from sunlight".

C is correct here. It captures the essence of the premises. Since organisms have been found to survive beyond the surface of earth, it could be the case of any other planet as well. Hence, a survey on the surface of any planet is insufficient to ascertain the non-existence of life in that planet.

The answer is clearly C.
The problem with E is that it concludes that if bacteria is found anywhere ( coal and oil in this instance), it proves that they had been feeding on substances that had not been produced by sunlight. This is not he conclusion of the argument.
Answer choice C clearly captures the essence of the argument i.e. Not all argument depends on sunlight. For evidence - microbial life and bacteria - both examples given of life forms existing not on the surface of the planet.)
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I would like to add,
I marked option E first but I gave a deep thought and here is my reasoning why E is wrong:

I believe Option E contains had been. "Had been" demonstrates an action in the past. Have been demonstrates action in the past that is continuing in the present.

From the given option we can say that bacteria did not use any energy by sunlight in the past but it cant be said whether it uses energy now, so are they continuing? We don't know. They did but maybe not now?

Let me know if my understanding is correct.

Is the ocean floor not considered a part of the earths surface? That is why I did not choose C, because I thought that was part of the earth's surface technically...

I'm stuck choosing between C and D. Can someone throw light on why D is wrong?

GMATNinja, can you please explain the meaning of 'C', how to interpret it and why is it the correct answer? Why is the thorough survey insufficient?
Also why is option 'D' wrong? Is it because we can't be sure if the life on those orbits is subjected to sunlight or not? Also would love to hear your take on how to understand the entire argument.

E is an assumption and not the main point of the passage.

C is more appropriate here and aligned with the main point of the passage

Each of these choices is offered as a potential conclusion to the argument.

That argument, so far, breaks down like this:

• Not all life depends on energy form sunlight. (for example...)
• ...Microbial life has been found in bedrock more than 5 KM below the Earth's surface.
• ...Bacteria have been found on the deep ocean floor, feeding on gases rising from the Earth's interior.

Now, which choice most follows as the logical conclusion to these statements?


Choice (C) states that if you thoroughly survey (i.e., examine) the surface of a planet, the information gained from that survey won't be enough to confirm that there is no life on this planet.

Surveying the surface of a planet, by definition, does not examine whether or not there is life below the surface. Even a thorough survey of the surface would not include, say, bacteria on deep ocean floors or microbial life 5km below the surface.

(C) follows logically from the prior statements because the prior statements tell us that life can exist far below the surface of a planet (in this case, Earth):

• Not all life depends on energy form sunlight. For example...
• ...Microbial life has been found in bedrock more than five KM below the Earth's surface.
• ...Bacteria have been found on the deep ocean floor, feeding on gases rising from the Earth's interior.
• Therefore, a thorough survey of a planet's surface is insufficient to establish beyond a doubt that the planet contains no life.

Looking at this another way, why is the author writing any of this in the first place? The author has just spent three lines and presented two pieces of evidence in order to show us that not all life depends on energy from sunlight. That's why (C) is such a good fit.

Now, let's take a look at choice (D):


Hm, well, we have no reason to question whether (D) is true or false... but that's irrelevant. Our task is to decide whether (D) fits into the passage as a logical conclusion to what the author's already presented. And this statement has no connection to the why of this passage.

Following up these statements with a conclusion that life probably exists on Sun-orbiting comments would be a wild logical detour that does nothing to build on the argument that the author has been building so far. That's why we eliminate (D).

I hope this helps break through the surface of this question! (I know... bad joke. I'm still working on my dad jokes. This one was bad enough to qualify, right?)
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Argument:
There are some life forms that do not depend on energy from sunlight.
For example: Microbial life found 5 kilometers below surface of earth
Bacteria found feeding on hydrogen and other gases rising from interior of earth

(A) The location in the bedrock where microbial life was found was not near a system of volcanic vents through which hydrogen and other gases rose from the interior of the Earth.
- All we know from the passage is life forms can survive without sunlight.
- The presence of volcano is a term used to misguide us in thinking that sunlight = heat from volcano. However, this is completely irrelevant
- Wrong

(B) Bacteria are able to exist at the molten center of the Earth.
- Again molten center is used to confuse us with sunlight = heat analogy --> Not true
- Wrong

(C) A thorough survey of a planet's surface is insufficient to establish beyond a doubt that the planet contains no life.
- This options states that we will not be able to decide whether there is life on a particular planet, just by scanning the surface.
- Why? Because life can be found in areas deep underground where sunlight cannot reach.
- Correct

(D) Life probably exists on Sun-orbiting comets, which are cold agglomerations of space dust and frozen gases.
- We cannot say so.
- The context of the argument is limited to presence of life with or without sunlight.
- This is out of context
- Wrong

(E) Finding bacterial remains in coal and oil would establish that the bacteria had been feeding on substances that had not been produced from the energy of sunlight.
- Tricky option
- This option is about bacteria living deep under the surface of earth - The passage is also discussing about such life forms = Relevant till now
- The rest of the option distorts the tenet of the passage. The passage is speaking about deriving energy from sources other than sun. This option focuses on deriving energy from sources that have not produced energy from sunlight
- Passage = living forms - sunlight
- Option = living forms - source - sunlight
- Wrong

For me I would say the question is talking about 2 things :- 1) Life deep inside earth’s surface 2) Life deep in ocean floor.

In Option (E) It is talking about a fact and which is only related to (1) Life deep inside earth’s surface. Option (E) is not covering the point (2) Life deep in Ocean floor.

Whereas the Option (C) is talking in a broader perspective it says just doing a survey of planet surface is not enough to determine that there is no life on planet i.e. there can be life deep inside the surface or in oceans.

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GmatNinja can u help with elimination of option B ? If "Bacteria are able to exist at the molten center of the Earth" then it supports the conclusion that sunlight is not essential.