Generally, a priori comparisons differ from a posteriori comparisons because A.the only correct way to calculate a priori comparisons is to perform them using SPSS. B. researchers choose to perform a priori comparisons when they want to test all possible simple comparisons. C. certain a priori comparisons are selected by the researcher based on predictions informed by the results of previous studies. D. choosing a priori comparisons means you will have no greater chance of Type I error than the probability of Type I error associated with the overall analysis of variance