anbknaga wrote:
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.
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?
Quote:
(C) A thorough survey of the planet's surface is insufficient to establish beyond a doubt that the planet contains no life.
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):
Quote:
(D) Life probably exists on Sun-orbiting comets, which are cold agglomerations of space dust and frozen gases.
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?)