Two Independent Random Samples of Sizes 5 and 7 Are $\mu _ { 1 } - \mu _ { 2 } ,$

Two independent random samples of sizes 5 and 7 are selected from two continuous distributions with means $\mu _ { 1 } - \mu _ { 2 } ,$ and that the two distributions have the same shape and spread. In testing $H _ { o } : \mu _ { 1 } - \mu _ { 2 } = 0 \text { versus } H _ { \pm } : \mu _ { 1 } - \mu _ { 2 } \neq 0$ using the Wilcoxon rank-sum test with approximate significance level of .05, the rejection region for the test is

A) either $w \geq 20 \text { or } w \leq 45$
B) either $w \geq 10 \text { or } w \leq 20$
C) either $w \geq 45 \text { or } w \leq 10$
D) either $w \geq 10 \text { or } w \leq 45$
E) either $w \geq 45 \text { or } w \leq 20$