Professor Smith Found a Relationship Between Education and Occupation

Multiple Choice

Professor Smith found a relationship between education and occupation. However, when age was introduced as a test factor, the relationship between education and occupation disappeared in the partials. In Professor Smith's study, age was introduced as a(n) :

A) control variable.
B) spurious variable.
C) distorter variable.
D) antecedent control variable.
E) intervening control variable.