Thousands of people have tonsillectomies every year and all live normal lives after the operation. We can conclude, from this observation, that the tonsils have no function in the body.
The argument would be most weakened by which of the following, if it were true?
A. People live normal lives after appendectomies but the
appendix is known to be part of the digestive system. (out of scope)
B. Another part of the body can take over the function of the tonsils if they are removed. (keep)
C. The tonsils have been shown to have a vital role to play in the physiology of laboratory
rabbits and guinea pigs. (out of scope)
D. The human tonsil develops as part of the immune system, a system of vital importance in defense against disease. (keep)
E. Tonsillectomies are performed only
when the tonsils become seriously infected. (out of scope)
Between B and D, B tells us exactly that tonsils have a vital part, but its function is taken over by other body part. D tells us that tonsil develops as part of immune system, but does not tell us whether it plays any vital role or not.
Hence, B is the best choice.