PT 58 S4 Q20

A recent study confirmed that salt intake tends toincrease blood pressure ... ...

Which one of the following, if true, contributes the most to an explanation of the results of the study?
(A) Study participants with high blood pressure who cut their salt intake only slightly during the study did not have significantly lower blood pressure by the end of the study.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Complete Section: LR-B, Sept. '09 LSAT (PT 58 Sec. 4)