See the question below.

A CRD with three factors: F1-fixed levels, F2-fixed levels, F3-fixed levels, was conducted. The experimenter obtained the following results from the AOV F-tests: the significant effects are F1 * F2 * F3 and F1 *F3. The following effects were not significant: F1 * F2, F2 * F3, F1, F2, F3 . She wants to determine which pairs of means are different across the levels of F1. Which of the following would be the most appropriate approach to answering her questions. A. Tukey's HSD applied to the levels of F1 separately at all combinations of (F2, F3). B. Tukey's HSD applied to the levels of F1 averaged over the levels of F3. C. Tukey's HSD applied to the levels of F1 averaged over all combinations of (F2, F3). D. Tukey's HSD applied to the levels of F1 separately at all levels of F3 averaged over the levels of F2. E. None of the above would be appropriate because the main effect of F1 was not significant