CR problem

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CR problem

by manishkd » Thu Aug 01, 2013 7:45 am
Red blood cells in which the malarial-fever parasite resides are eliminated from a person's body after 120 days.
Because the parasite cannot travel to a new generation of red blood cells, any fever that develops in a person
more than 120 days after that person has moved to a malaria-free region is not due to the malarial parasite.
Which of the following, if true, most seriously weakens the conclusion above?
(A) The fever caused bythe malarial parasite mayresemble the fever caused by flu viruses.
(B) The anopheles mosquito, which is the principal insect carrier of the malarial parasite, has been eradicated
in many parts of the world.
(C) Many malarial symptoms other than the fever, which can be suppressed with antimalarial medication, can
reappear within 120 days after the medication is discontinued.
(D) In some cases, the parasite that causes malarial fever travels to cells of the spleen, which are less
frequently eliminated from a person's body than are red blood cells.
(E) In any region infested with malaria-carrying mosquitoes, there are individuals who appear to be immune
to malaria.

I am confused between C and D, though OA is D
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by [email protected] » Thu Aug 01, 2013 6:18 pm
Hi manishkd,

This CR prompt tells us some facts, then draws a conclusion:

Facts:
1) Malarial-fever parasite that resides in red blood cells are eliminated from the body in 120 days.
2) The parasite can't travel to new red blood cells
3) The parasite can cause a fever

Conclusion:
After 120 days (if you're in a malarial-free area), then any fever you get is NOT from the parasite.

The author assumes that the ONLY way that the parasite can cause a fever is through the blood (and that it has to happen within 120 days). One of the ways to weaken the prompt is to find an answer that states that there's another way that the parasite can cause a fever (and it probably has something to do with going past the 120 day limit).

Answer C talks about symptoms OTHER than fever, which is not what the prompt is talking about. Answer D talks about how the parasite actually stays in the body longer than 120 days (just in a different part of the body) and can last past 120 days.

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by manishkd » Thu Aug 01, 2013 6:27 pm
Thanks Rich for nice explanation.
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by ShalakaK » Fri Aug 02, 2013 1:05 pm
Hi Rich,
In D, the words "In some cases" confuse me. (Nevertheless, the rest of the sentence does make sense)
The argument seems to be general.

How do w assume this applies to all the cases?
Could you please explain?

Thanks

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by [email protected] » Fri Aug 02, 2013 4:12 pm
Hi ShalakaK,

The phrase "in some cases" is referred to as "soft language"; this type of language tends to be in the correct answer in CR questions (as opposed to the phrase "in ALL cases", which is "extreme" and usually incorrect).

The author states that "any fever that develops ....more than 120 after...is NOT due to the malarial parasite", so an easy way to weaken this author's point is to prove that the malarial parasite CAN, in some way, cause a fever after 120 days. We don't need to say that it "always does", we just need to say that it's possible AND find a reason why it's possible. So, we're back to D.

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