In the Formula $\bar { x } \pm z _ { \alpha / 2 } ( ?/ \sqrt { n } )$

Multiple Choice

In the formula $\bar { x } \pm z _ { \alpha / 2 } ( ?/ \sqrt { n } )$
,the subscript $( \alpha / 2 )$ refers to the:

A) probability that the confidence interval will contain the population mean.
B) probability that the confidence interval will not contain the population mean.
C) area in the lower tail or upper tail of the sampling distribution of the sample mean.
D) level of confidence.
E) sampling error.