Consider the regression model

Salary=β1+β2WorkExperience+u

.

Suppose we have another variable Region which captures where the individuals in our data set live, and 

We believe that Region affects the intercept of the linear relationship between Salary and WorkExperience. If we wish to account for this in our model, we need to include _____ additional regressors in our regression model.

A. 6

B. 3

C. 7

D. 4