If a Company's Variable Costs Per Unit Were to Increase

If a company's variable costs per unit were to increase but its unit selling price stays constant,the effect on a profit-volume graph would be that the

A) contribution margin line would shift upward parallel to the present line.
B) contribution margin line would shift downward parallel to the present line.
C) slope of the contribution margin line would be pronounced (steeper) .
D) slope of the contribution margin line would be less pronounced (flatter) .