If the Selling Price Per Unit and the Variable Cost

If the selling price per unit and the variable cost per unit both increase by 5%, what is the effect on the contribution margin per unit and on the contribution margin ratio? $\begin{array}{ll}\text { Contribution margin per unit }&\text { Contribution margin ratio }\\\hline\text { a) Increase } & \text { Increase } \\\text { b) Increase } & \text { No effect } \\\text { c) Decrease } & \text { No effect } \\\text { d) Decrease } & \text { Increase }\end{array}$