An investigator rates severity of a muscle condition using visual inspection of muscle biopsies between 1 (normal), 2 (mild), 3(moderate), and 4 (severe). She wants to compare between two groups: 14 subjects treated with a new drug, and 12 subjects treated with a placebo. Which test should she use? a. Mann-Whitney U test b. Two-independent sample t-test for means c. t-test for paired samples.