The Correlation in a Large Company Between Self-Confidence and Income

Multiple Choice

The correlation in a large company between self-confidence and income is 0.25. After controlling for level of authority on the job, the original correlation dips to 0.11. What is this evidence of?

A) a direct relationship between self-confidence and income
B) a spurious relationship between self-confidence and income; job authority causes both
C) an intervening relationship between self-confidence and income; self-confidence affects income through increasing people's job authority
D) either a spurious or an intervening relationship; it is impossible to differentiate the two possibilities on statistical grounds