Although the ratio of physicicans to total population is about the same in the United States and Canada,the United States has 33 percent more surgeons per capita.Clearly,this is the reason people in United States undergo 40 percent more operations per capita than do Canadians.
The explanation given above rests on an assumption that
(A)patients in the United States do not have a greater need for surgery than do patients in Canada.
(B)the population of the United States is not larger than that of Canada.
(C)United States patients sometimes traval to Canada for certain kinds of surgery.
(D)general practitioners in the United States do not as a rule examine a patient who is a candidate for surgery before sending the patient to a surgeon.
(E)there are no surgical operations performed in Canada.
The best answer is A.But I am confused.Any people can do me a favor to explain why A?Thanks!
The Key is to understand the conclusion: Clearly,this( more surgeons in US than in canada) is the reason people in United States undergo (40 percent more operations per capita )than do Canadians.===> read again, please, that is saying: " more surgeons-> more operations"===> so, the assumption which is you must rule out to support the conclusion is A.:patients do not have a (greater need )for surgery .
