You want to test a supplement's efficacy in an experiment but you also want to try to account for the variance within individuals. You select 10 subjects and test them on a depression scale prior to giving them the supplement, and then test them again three weeks after giving them the supplement. Using the data below, conduct a two-tail, Within-subjects, or Dependent Sample t-test, with an alpha = 0.05. Subjects Pretest Posttest 1 15 13 2 16 12 3 12 13 4 16 11 5 24 22 6 14 13 7 16 14 8 12 14 9 13 13 10 19 17 What is the t-statistic for this test? O t(18) = 0.99 O t(9) = 2.24 O t(18) = 2.24 O t(9) = 0.99