Hi Everyone,

Could anyone please help me in understanding the answer of the following CR question:

There is a great deal of geographical variation in the frequency of many surgical procedures -- up to tenfold variation per hundred thousand people between different areas in the numbers of hysterectomies,prostatectomies, and tonsillectomies.

To support a conclusion that much of the variation is due to unnecessary surgical procedures, it would be most important to establish which of the following?

(A)A local board of review at each hospital examines the records of every operation to determine whether the surgical procedure was necesaary.
(B)The variation is unrelated to factors(othher than the surgical procedures themselves) that influence the incidence of diseases for which surgery might be considered.
(C)There are several categories of surgical procedure (other than hysterectomies,prostatectomies, and tonsillectomies) that are often performed unnecessarily.
(D)For certain surgical procedures, it is difficult to determine after the operation whether the procedures were necessary or whether alternative treatment would have succeeded.
(E)With respect to how often they are performed unnecessarily, hysterectomies,prostatectomies, and tonsillectomies are representatives of surgical procedures in general.

The OA is B.

Regards,
AndyB.