Evaluate argument

This is a really interesting CR question.

I also would like to know how can we determine the correct answer? What is the best approach?

Experts, we need your help. Thanks.

Roland2rule wrote:Lists of hospitals have been compiled showing which hospitals have patient death rates exceeding the national average. The data have been adjusted to allow for differences in the ages of patients.
Each of the following, if true, provides a good logical ground for hospitals to object to interpreting rank on these lists as one of the indices of the quality of hospital care EXCEPT:
(A) Rank order might indicate insignificant differences, rather than large differences, in numbers of patient deaths.
(B) Hospitals that keep patients longer are likely to have higher death rates than those that discharge patients earlier but do not record deaths of patients at home after discharge.
(C) Patients who are very old on admission to a hospital are less likely than younger patients to survive the same types of illnesses or surgical procedures.
(D) Some hospitals serve a larger proportion of low-income patients, who tend to be more seriously ill when admitted to a hospital.
(E) For-profit hospitals sometimes do not provide intensive-care units and other expensive services for very sick patients but refer or transfer such patients to other hospitals.

Premise: Hospitals have been ranked in terms of patient death rates.
Conclusion: A hospital's rank should not be used to judge the quality of hospital care.

Question stem:
Each of the following, if true, provides a good logical ground for hospitals to object to interpreting rank on these lists as one of the indices of the quality of hospital care EXCEPT:
Ignore the word EXCEPT.
Instead, answer the following question:
Which of the following, if true, provides a good logical ground for hospitals to object to interpreting rank on these lists as one of the indices of the quality of hospital care?
Eliminate the four answer choices that support the conclusion.

A: Rank order might indicate insignificant differences.
Here, the difference between a high-ranking hospital and a low-ranking hospital might be insignificant, strengthening the conclusion that a hospital's rank should not be used to judge the quality of hospital care.
Eliminate A.

B: Hospitals that keep patients longer are likely to have higher death rates than those that discharge patients earlier but do not record deaths of patients at home after discharge.
Here, a hospital's rank does not take into account patients who die shortly after discharge, strengthening the conclusion that a hospital's rank should not be used to judge the quality of hospital care.
Eliminate B.

D: Some hospitals serve a larger proportion of low-income patients, who tend to be more seriously ill when admitted to a hospital.
Here, a hospital in a low-income area is likely to have a higher death rate not because it provides low-quality care but because its patients are more seriously ill, strengthening the conclusion that a hospital's rank should not be used to judge the quality of hospital care.
Eliminate D.

E: For-profit hospitals sometimes do not provide intensive-care units and other expensive services for very sick patients but refer or transfer such patients to other hospitals.
Here, a hospital might have a low death rate not because it provides high-quality care but because it transfers very sick patients to other hospitals, strengthening the conclusion that a hospital's rank should not be used to judge the quality of hospital care.
Eliminate E.

The correct answer is C.

C: Patients who are very old on admission to a hospital are less likely than younger patients to survive the same types of illnesses or surgical procedures.
This information is unhelpful, since it is unknown whether poorly-ranked hospitals tend to admit patients who are very old.