单选题 An analyst does research about confidence interval. The range of a confidence interval is most likely determined by the product of the reliability factor and the:
A. standard error.
B. mean.
C. degree of confidence.

【正确答案】 A
【答案解析】[解析] 置信区间是由均值加和减依赖因子(根据显著性水平和置信度确定)乘以标准误差来确定的，因此它们的间距(最大值和最小值的差)就等于两倍的依赖因子乘以标准误差。