单选题 The IPCC announcement three years ago that "most of the warming observed over the last 50 years is" ______.

A、 possibly due to human activities
B、 possibly because human activities
C、 due to likely human activities
D、 human activities likely attributable

【正确答案】 A

【答案解析】[分析] 短语题型。根据第二段第二句The IPCC announced in 2001 that “most of the warming ob served over the last 50 years is likely to be attributable to human activities”．中的 attributable to指“可归于……的”；C项的due to指“由于，应归于”；be cause是连词后面跟从句，因而应排除B。修饰due to的副词不应放在to的后面，因而排除C。D不符合表达习惯。