In a (Fictional) Series of Quasi-Experimental Studies, Low Self-Esteem Was

Multiple Choice

In a (fictional) series of quasi-experimental studies, low self-esteem was found to be correlated with preference for contact sports (e.g., hockey) . However, researchers subsequently discovered that the relationship between self-esteem and contact sports was only present in people who had had their wisdom teeth removed when they were young. In this example, wisdom teeth best reflects what type of variable?

A) moderator variable
B) mediator variable
C) extraneous third variable
D) unidirectional causal variable