Individuals in four different age groups are asked to rank, on scale of 1 to 10, three flavors of ice creams. Median rankings from the individuals are grouped by the flavor of ice cream and by age groups. Each group has the same number of individuals. Which nonparametric test could be used to see if there is a difference in flavor preferences among the three age groups.
A. Wilcoxon Signed Rank Test. B. Friedman test.
C. Mann-Whitney test. D. Kruskal-Wallis test.