PT 61 S2 Q10

In a vast ocean region, phosphorus levels have doubledin the past few decades ... ...

Which one of the following can be properly inferred from the information above?
(A) The agricultural runoff pouring out of the river contributes to the growth of plankton near the ocean surface.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Complete Section: LR-A, Oct. '10 LSAT (PT 61 Sec. 2)