【正确答案】 B

【答案解析】[听力原文]
   U.S. Government scientists reported Wednesday that last year's temperatures—on average— were the warmest ever recorded. "2015 compared to the long-term record was more than a degree and a half Fahrenheit warmer than the twentieth century average, which is quite a bit."
   The U.S. weather and space agencies say temperatures recorded in 2015 were the highest in 136 years of record keeping. Scientists say the increased temperatures are the result of the buildup of greenhouse gases in the atmosphere.
   What did the scientists say about the temperatures on average last year?
此题问的是科学家对于去年平均温度的看法。第一句提到去年的平均温度是有记录以来最温暖的。故答案为B。