microbe species---Not convinced with the answer!!

Looks like you've got a good point!

The author provides a great deal of evidence about how and why individual species of microbe can't be isolated. His conclusion, based on that evidence, is that microbiologists don't fully understand those microbes. The glaring hole in the argument is the assumption that biologists can only understand things that they isolate. This leads us to (C) as the closest answer.

(B) is the right answer to the wrong question type. The first two sentences of evidence can be pieced together to logically infer that (B) must be true. However, this is an Assumption question, not an Inference question. Assumptions are unstated facts that are necessary for the conclusion to follow from the evidence. If they are true, the author's conclusion is properly drawn, but if they are proven false then the author's conclusion is undermined despite his facts being otherwise correct. (B) must be true as a consequence of his data, and (B) does not tie into his conclusion at all; for these two reasons, we can rule it out.

However, you're correct that we've made an error. The proper assumption is that no microbiologist can understand a microbe unless some microbiologists can isolate the bug. Indeed, it doesn't have to be the same one doing the isolating and the understanding. We've made a typo, and if you'll shoot me a PM with the source of the problem and a page number or problem ID number, I'll make sure it get's added to the errata sheet ASAP!

Though I have also opted C first,but because of the reason explained above I didn't choose it and went for option B. I think now its clear that B can't be the answer and C also has some problem with it But OA is C only.

vj, thanks for the PM. I actually have to backtrack--this problem doesn't have a mistake. However, what we do have here is an illustration of why LSAT problems aren't necessarily the best practice for the GMAT!

One of the major subjects tested by the LSAT is the difference between a 'sufficient' assumption and a 'necessary' assumption. Here is an example:

If a house is far from the city and either small or poorly constructed, it will be cheap. Clearly, my house was inexpensive

Necessary assumption: my house is far from the city. This must be true for my logic to be sound: if my house is close to the city, then my premises don't connect to my final conclusion and my argument is nonsense. However that assumption isn't enough in and of itself! My house also needs to be either small or cheaply built for us to be certain.

Sufficient assumption: My house is far from the city and small. This doesn't have to be true--my house could be far from the city and poorly built. But if it is true, then that is sufficient to prove my conclusion accurate 100% of the time.

The GMAT rarely distinguishes between these two, but the LSAT often tests both ways--and what we have here is a question of the latter. The prompt asks us what "enables the conclusion to be properly drawn," or in other words, which answer choice guarantees that the evidence logically leads to the conclusion. If (C) is true, then the conclusion is true--so it's the unambiguous right answer.

i chose c too cause it easily was tied to the conclusion, which is the last sentence. negate that conclusion and the arguments falls apart.

C links isolation and complete knowledge

only C goes the best................!!!!

negate statment C and the conclusion will no longer stand...hence , C is the assumption

Cause and Effect

Which one makes fore sense:

1. It is currently impossible to cultivate any one such species in isolation. Therefore microbiologists lack complete knowledge of most microbe species.

2. Microbiologists lack complete knowledge of most microbe species thus it is currently impossible to cultivate any one such species in isolation.

I think 1. is better because claiming that microbiologists lack complete knowledge of most microbe species. is out of scope for the passage; while 2. is more in line with the passage.

C is a good explanation for 2.

Option C seems to be correct here which states the assumption.

Using POE, C is left even though test takers hardly comprehend the idea of "complete knowledge".
E is wrong because the passage states that it is impossible to cultivate any one of "almost species".

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