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?
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?
The correct option is 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.
Option (d)
The passage concludes that, because the malarial parasite cannot reside in red blood cells for more than 120 days, the malarial parasite cannot cause fever more than 120 days after infection. However, according to D, there is a site in the body where the parasite could reside for more than 120 days after infection. Therefore, D weakens the conclusion and is the best answer. The resemblance between malarial-fever symptoms and those of other diseases, the existence of other malarial symptoms, and the possibility of immunity to malaria are irrelevant to the issue of the conditions under which malarial fever can occur. B provides confirmation for the existence of malaria-free regions but does not otherwise bear on the conclusion.
Option (d)
The passage concludes that, because the malarial parasite cannot reside in red blood cells for more than 120 days, the malarial parasite cannot cause fever more than 120 days after infection. However, according to D, there is a site in the body where the parasite could reside for more than 120 days after infection. Therefore, D weakens the conclusion and is the best answer. The resemblance between malarial-fever symptoms and those of other diseases, the existence of other malarial symptoms, and the possibility of immunity to malaria are irrelevant to the issue of the conditions under which malarial fever can occur. B provides confirmation for the existence of malaria-free regions but does not otherwise bear on the conclusion.
