Do One of the Following, as Appropriate: (A) Find the Critical

Multiple Choice

Do one of the following, as appropriate: (a) Find the critical value $z _ { \alpha / 2 }$ , (b) find the critical value $t _ { \alpha / 2 }$ .
$99 \% ; n = 17 ; \alpha$ is unknown; population appears to be normally distributed.

A) $z _ { \sigma / 2 } = 2.583$
B) $z _ { \sigma / 2 } = 2.567$
C) $t _ { \sigma / 2 } = 2.921$
D) $t _ { \sigma / 2 } = 2.898$