求助-GWD逻辑一题答案！

没有找到这题的答案，哪位同学知道正确选项，麻烦请告知！  多谢！！

Because visual inspection cannot reliably distinguish certain skin discolorations from skin cancers, dermatologists at clinics have needed to perform tests of skin tissue taken from patients.  At Westville
                Hospital, dermatological diagnostic costs were reduced by the purchase of a new imaging machine that diagnoses skin cancer in such cases as reliably as the tissue tests do.  Consequently, even though the machine is expensive, a dermatological clinic in Westville is considering buying one to reduce diagnostic costs.

Which of the following would it be most useful for the clinic to establish in order to make its decision?

1. Whether the visits of patients who require diagnosis of skin discolorations tend to be shorter in duration at the clinic than at the hospital

2. Whether the principles on which the machine operates have been known to science for a long time

3. Whether the machine at the clinic would get significantly less heavy use than the machine at the hospital does

4. Whether in certain cases of skin discoloration, visual inspection is sufficient to make a diagnosis of skin cancer

5. Whether hospitals in other parts of the country have purchased such imaging machines

我觉得选C,要考虑机器的使用率.大医院敢买,因为它可以通过多次的诊断使用来填补COST,而小诊所就不一定了,如果很少人使用的话,就很难填补缺损的钱.

Money speaks louder than anything else.~~