The Wilcoxon signed rank test, involves the usage of the sign and the magnitude of the rank of the differences between pairs of measurements, and it is a non-parametric alternative to the paired t test when the population distribution of the differences is not normally distributed. In this problem, the results are tied to each other, for example there is an effect, and outcomes of a variable are collected before the effect and after the effect on some observations. For example, a group of patients’ blood pressure can be measured before and after a medicine is taken. Wilcoxon Signed Rank Test does not require the normality assumption that we usually see on a parametric test. Steps of the Method In this test, the alternative hypotheses are constructed in three different ways. The hypotheses are shown as follows. H0 :The distribution of differences is symmetrical around MD = 0 H1a :The differences tend to be larger than MD = 0 H1b :The differences tend to be smaller than MD = 0 H1c :The differences tend to be larger than MD = 0 or smaller than MD = 0. The correct answer is D.