Twenty-one executives in a large corporation were randomly selected for a study in which several factors were examined to determine their effect on annual salary (expressed in $000s). The factors selected were age (in years), seniority (in years), years of college, number of company divisions they had been exposed to and the level of their responsibility. A regression analysis was performed using a popular spreadsheet with the following results: Constant 23.00371
Std Error of Y estimate 2.91933
R^2 0.91404
No. of Observations 21
Degrees of Freedom 15

Age Seniority Years of College #Divisions Level
X Coefficients -0.031 0.381 1.452 -0.089 3.554
Cofficient of Std Error 0.183 0.158 0.387 0.541 0.833

Which one of the following is the dependent variable?

a. Age
b. Seniority
c. Level of responsibility
d. Annual salary