If n = 15 for each sample, which of the following sets of data provides the clearest difference between the two samples?
1) a sample mean difference of 10 points with s2 = 10 for both samples
2) a sample mean difference of 5 points with s2 = 10 for both samples
3) a sample mean difference of 10 points with s2 = 5 for both samples
4) a sample mean difference of 5 points with s2 = 5 for both samples