继续问feifei笔记题

6．Although the ratio of physicians to total population is about the same in the United
                State and Canada, the United States has 33 percent more surgeons per capita. Clearly, this is the reason people in the 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 travel 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 unnecessary surgical operations performed in Canada.

答案选A，可是我看不懂题，请大家帮忙解释一下，

下面两句不是都在说平均每个人的手术么？这不是相互矛盾的？
            

the United States has 33 percent more surgeons per capita.

40 percent more operations per capita than do Canadians