A researcher uses a factorial ANOVA to statistically analyze the effects of four types of training strategies and three levels of self-efficacy on a measure of job performance. The results indicate that there are signfiicant main effects of each independent variable and a significant interaction. The researcher will conclude that:

a. training is effective regardless of level of self-efficacy

b. each type of training is equally effective for each level of self-efficacy

c. the most effective type of training depends on the level of self-efficacy

d. overall, training is effective only for people with a certain level of self-efficacy