A researcher conducts an experiment on the effects of caffeine on memory. They hypothesise that caffeine may only be effective for studying if a person also has caffeine during the later testing of memory (say in an exam). There are two IV's: caffeine use during study (yes/no) and during testing (yes/no).

If there was a significant result, what would be the best way for the researcher to examine this further:

A. Simple effects analyses

B. Homogeneity of Variances

C. Using z-scores

D. The ANOVA gives you all of the relevant information that you need