问题
单项选择题
According to the author, climate researchers ______.
A．are quite sure about why it's getting hotter and hotter
B．declared that we humans are the cause why it's getting hotter
C．have discussed the possible causes why it's hotter
D．have claimed that changes in nature are the roots of hot days
答案
参考答案：C
解析：[分析] 推断题型。 从第二段第一句话Scientists have argued about whether temperature rises are due to human activities or due to natural changes in our environment．中的“argue”和“whether”两个词得知科学家们并不确信，因而C项正确。