[求助]请大家都来帮我看看这道逻辑题

Although the ration of physicians to total population is about the same in US and canada, US has 33% more surgeons per capita.Clearly, this is the reason people in US undergo 40% more operations per capita than do Canadians. The explaination given above rests on an assumption that:

A, patients in US do not have a greater need for surgery than do patients in Canada.
B, the population of US is not larger than that of Canada.
C, US patients sometimes travel to Canada for certain kinds of surgery.
D, general practitioners in US 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.

大家说说吧。

再问这题是前半部分是原因 而后推出后半个结果。还是后半部分是原因 而后得出前面的结果?

A, an interesting question, I think the reasoning is

physicians/total population is the same in US and canada,US has 33% more surgeons per capita   cause   people in US undergo 40% more operations per capita than do Canadians.

So Only A eliminate other reasons to cause the conclusion and is the assumption. other choices are all irrelevant.