A Company Has Undertaken a Study of 16 Secretaries' Yearly

A company has undertaken a study of 16 secretaries' yearly salaries (in thousands of dollars) .They want to predict salaries from several other variables.
The variables considered to be potential predictors of salary are:
X1 = months of service
X2 = years of education
X3 = score on standardized test
X4 = words per minute of typing speed
X5 = ability to take dictation in words per minute
A multiple regression model with all five variables was run,resulting in the following output:

= 0.958
-Which measurement is the worst predictor of salary,after allowing for the linear effects of the other variables in the model?

A) months of service
B) words per minute of typing speed
C) ability to take dictation in words per minute
D) score on standardized test
E) years of education