If the hypothesis that CJD is caused by prions is correct, finding the ... ...

If the hypothesis that CJD is caused by prions is correct, finding the answer to which one of the following questions would tend most to help a physician in deciding whether a patient has CJD?
(A) Has the patient suffered a severe blow to the skull recently?
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in PT70 (Oct 2013): Reading Comprehension