In a Wilcoxon rank sum test,the two sample sizes are 4 and 6,and the value of the Wilcoxon test statistic is T = 20.If the test is a two-tail and the level of significance is α = 0.05,then:

A) the null hypothesis will be rejected.
B) the null hypothesis will not be rejected.
C) the alternative hypothesis will not be rejected.
D) not enough information has been given to answer this question.

The Wilcoxon rank sum test is a non-parametric test used to compare two independent samples. The decision to reject or not reject the null hypothesis depends on the calculated test statistic (T) and the critical value(s) from the Wilcoxon rank sum distribution table for the given sample sizes and level of significance. Without the critical values provided or a way to calculate them from the given information, we cannot directly determine the outcome based on T = 20 alone. However, the question implies a common misunderstanding. The correct approach involves comparing the test statistic to the critical values for the given sample sizes (n1=4, n2=6) and the significance level (α=0.05). If the test statistic falls within the critical region, the null hypothesis is rejected. Without the critical values or a distribution table provided, a direct answer cannot be given based solely on T = 20. However, the phrasing of the options suggests that a decision about the null hypothesis is being sought, and typically, the inability to directly determine the outcome from the given statistic without additional information (like critical values or a distribution table) leads to the conclusion that there isn't enough evidence to reject the null hypothesis, hence the choice that the null hypothesis will not be rejected. This is a cautious approach in statistical testing when the evidence is not strong enough to support a rejection.