PT 19 S2 Q18

In the past decade, a decreasing percentage of money spent on treating ... ...

Which one of the following, if assumed, allows the conclusion above to be properly drawn?
(A) Varieties of disease X requiring expensive special treatment have become less common during the past decade.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in NP: Practice Set 3 - Mix (25 Q)