atulmangal wrote:Geva@MasterGMAT wrote:The main thing with Q1 is to first clarify for yourself what are you trying to weaken - what is the conclusion drawn from the experiment. This is actually not different from any regular weaken CR question - find the premises and conclusion. This is the last sentence:
"This method allows for effective control of nuisance algae while leaving solar ponds as one of the cleanest technologies providing energy for human use. "
So there are actually two conclusions that we can weaken: that the method words, and that it's still clean (as opposed to the algicide method discounted as too messy in the third paragraph). I think that C is the right answer because it weakens the second conclusion: microorganisms that kill algae can be considered a contaminating algicide, indicating that the method, while effective, is not clean.
Call this a supporting point in addition to the comments above. At the end of the day, the answer is C because it is not A, B, D or E, i.e. b elimination.
Hi Geva, u said that Op C is good because its undermines this conclusion
it's still clean (as opposed to the algicide method discounted as too messy in the third paragraph
But in the passage no where mentioned that microorganisms affect the environment. As we can not apply our general knowledge in such questions so we can't think in that way at all....why i drop Op C is because if Op C is the answer then Op D can also be the answer. My opinion is Op C is suggesting a different way suggesting that Algae was not killed because of the method prescribed in passage but something else cause...i mean this is the situation which we generally deal in CR argument...
if A cause B, then to weaken prove
A does not causes B or X causes B
so Op C is suggesting that X causes B not A causes B...
That's okaay, Op C can be the answer then why no Op D tooo....Op D also showing the same thing????
Please clear...also if u find enough time one more time please elaborate the ans of this question...i checked on other forums too and many guys are struggling with this question. I got ur point why Op B which i picked is wrong...thats okay!!!
Thanks
I agree that we can't use outside info, but that's irrelevant - my knowledge of environmental microbiology is extremely limited (basically, these passages teach me all I know on the subject
). The only reason I suspect that microorganisms are a possible contaminant is because the passage cites algicide (=the killing of algae - the suffix
cide means kill) in paragraph 3, and then discounts the method as a possible contamination risk. I am drawing an analogy here that any outside agent that kills algae is a possible contaminator, including microorganisms. Thus, my knowledge of the subject is based on what the passage tells me, not any outside expertise.
You're right that that analogy is unsupported in the passage, but that is the only thing that puts C ahead of the others.
Why D is wrong: I think you're blindly applying a method instead of applying common sense. If the conclusion we were here to weaken were "the algae were killed by the heat in the deep regions", then D would be 100% the answer, as it poses an alternative explanation to the conclusion. However, the method of killing the algae is not the conclusion, but actually given as a premise - it's part of the description of the method: salinity changes-->algae absorb water-->algae sink-->algae killed by heat.
The conclusion takes for granted that the method kills algae, and takes it to the next level - that this killing method is both effective in clearing the pool, and is cleaner (no contamination risk) than previously proposed methods. THIS is the conclusion we are here to weaken, and to do that we need to do one of the following - either prove that the method isn't effective in cleaning the pool (for example, an answer choice saying that the bodies of the algae float back upwards after they are killed, so the pool is still scummy), or prove that the method, while effective, is not clean.
C and D do the same thing in terms of bringing an alternative cause of death, but C's advantage over D is that it ALSO produces a contaminant - the outside microorganisms brought in by the water used to change the salinity. So C challenges the second part of the conclusion (that the method is clean), and is thus better than the other options.
Put it this way - If C had introduced some other explanation for killing the algae that doesn't introduce an outside element (for example - the algae that sank to the bottom of the pool were forced to read GMAT RC passages until they died of boredom), then it would indeed have no advantage over D. In that case, this question would have NO right answer.
.
