Tukey's Multiple Comparison Procedure is used for inference of

a. Difference between two-factor level means

b. Contrasts

c. Single-factor level means

d. All of the above

Tukeys Multiple Comparison Procedure is a type of post hoc test. Therefore, this indicates that after an initial statistical test has given significant results indicating a significant difference between group means, post hoc testing is used to find where the differences between groups means are located.

Option B, contrasts, is not appropriate as it would use a t-test to establish if there were a significant difference between specified contrast values.

If option B is not appropriate, then option D is also not appropriate.

As post hoc testing is likely most common following a one way analysis of variance (ANOVA), it is likely that option C, single-factor level means is the most appropriate option.

When there is more than one factor in an analysis this changes the structure of the data and the variables and therefore, the overall analysis, which would make option A less likely and once again, option C, the most appropriate.