What is a valid statement regarding one-tailed and two-tailed tests? Question 19 options: For a two-tailed test, if the test statistic is either greater than the upper critical value or less than the lower critical value, the decision would be to fail to reject the null hypothesis. For a lower one-tailed test, if the test statistic is less than the critical value, the decision would be to fail to reject the null hypothesis. For standard normal and t-distributions, which have a mean of zero, lower-tail critical values are negative and upper-tail critical values are positive. For an upper one-tailed test, if the test statistic is greater than the critical value, the decision would be to fail to reject the null hypothesis