Critical Reasoning

58. 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 by the malarial parasite may resemble 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.


My answer was C but correct answer is D.....I chose C because i did not like 'in some cases' How wil u explain this?

src_saurav wrote:58. 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 by the malarial parasite may resemble 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.

Premise: Red blood cells in which the malarial-fever parasite resides are eliminated from a person's body after 120 days.
Conclusion: 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.

The conclusion here is EXTREME, suggesting that it is IMPOSSIBLE to contract malaria after moving to a malaria-free region.
To weaken the conclusion, the correct answer must show that it is POSSIBLE to contract malaria after moving to a malaria-free region.

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
This option show how it is possible to contract malaria after moving to a malaria-free region: the parasite can reside in the spleen.

The correct answer is D.