When examining group difference where the direction of the difference is specified,which of the following is used?

A) two-tailed test
B) one-tailed test
C) directional hypothesis
D) critical value

A one-tailed test is used when the direction of the difference is specified, meaning that we are only interested in whether one group is significantly higher or lower than another group. This is in contrast to a two-tailed test, which tests for a difference in either direction. A directional hypothesis is also used when the direction of the difference is specified, as it is a prediction of the direction of the effect. A critical value is the cutoff point for determining whether a result is statistically significant, and is used in both one-tailed and two-tailed tests. However, the question specifically asks about the best choice for examining group differences with a specified direction, so the answer is B (one-tailed test).