Ilike really, really, really need ..

ashley calculates her salary (base and commission) for the year "y" using the model y = 0.2x + 25,000; where x represents her total sales for the year. what is the meaning of the y-intercept in the model?
a) the y-intercept represents ashley's base pay
b) the y-intercept represents ashley's commission pay
c) the y-intercept represents ashley's total sales for the year
d) the y-intercept represents the highest salary ashley can earn