In the Formula $\bar { x } \pm z _ { a / 2 } \sigma / \sqrt { n }$

Multiple Choice

In the formula $\bar { x } \pm z _ { a / 2 } \sigma / \sqrt { n }$ , the $\alpha$ / 2 refers to:

A) the probability that the sample mean will not equal the population mean.
B) the probability that the confidence interval will not contain the population mean.
C) the level of confidence.
D) None of these choices.