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 is 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 anti-malarial
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.

OA after some discussion...