A clinical trial compares the effects of three different antihypertensive medications (Drug A, Drug B, and Drug C) on systolic blood pressure reduction. One hundred twenty patients are randomized equally into the three groups, and after 8 weeks of therapy, the mean ± SD reductions in systolic blood pressure are: Drug A, 15 ± 5 mm Hg; Drug B, 18 ± 6 mm Hg; Drug C, 12 ± 4 mm Hg. A one-way ANOVA yields a p-value of 0.01, indicating a significant overall difference among the three groups. To determine which specific drug pairs differ significantly while maintaining an overall Type I error rate of 0.05, which post-hoc test is most appropriate?