Which of the following hypotheses do the experimental data best support？

A. Increasing precipitation levels bring increasing amounts of airborne sulfate emissions into the lakes.
B. Increasing air temperatures have the effect of increasing pH levels in the lakes, which in turn increase sulfate-concentration levels in the lakes.
C. The melting of glacial ice due to gradually increasing air temperatures increases the amount of sulfates in lake water.
D. Wide variations in precipitation levels contribute to wide variations among the lakes in both pH and sulfate-concentration levels.