Adam calculates his annual commission, y, using the model y = 0.28x, where x represents his total sales for the year. What is the meaning of the x-intercept in the model?

A) the x-intercept represents Adam's base pay

B) the x-intercept represents the highest salary Adam can earn

C) the x-intercept represents Adam's total sales when he earned no commission

D) the x-intercept represents Adam's commission pay when he had zero total sales