Suppose Three Students Were Interested in Studying the Association Between

Suppose three students were interested in studying the association between a person's political party (Democrat, Republican, Independent, or Other) , and whether they voted in the last election (Yes, No) . Each of the three students selects a random sample of 40 students and asks each student their political party and if they voted in the last election. Their three Mean Group Diff statistics are:
Mean Group Diff 1 = 0.12 Mean Group Diff 2 = 0.35 Mean Group Diff 3 = 0.27
Which Mean Group Diff statistic provides the strongest evidence against the null hypothesis?

A) 0.12
B) 0.35
C) 0.27