A randomized controlled trial assesses the effects of a treatment for multiple sclerosis on functioning in three groups of adults. Investigators assess global functioning which an ordered, Likert-type scale (not continuous data). Which one of the following statistical tests is the most appropriate to assess differences in functioning between the groups? A) Kruskal-Wallis B) Multivariate ANOVA C) One way ANOVA D) Analysis of covariance (ANCOVA) E) Multiple Linear Regression