阅读下列短文, 从给的四个选项 (A、B、C和D) 中, 选出最佳选项。
(2013·南昌市二模，C)
“Plants were expected to get larger with increased carbon dioxide in atmosphere, but changes in temperature, humidity and nutrient availability seem to trumped the benefits of increased carbon dioxide，” said researchers from the National University of Singapore.
