E plc operates a marginal costing system. For the forthcoming year, variable costs are budgeted to be 60% of sales value and fixed costs are budgeted to be 10% of sales value. If E plc increases its selling prices by 10%, but if fixed costs, variable costs per unit and sales volume remain unchanged, the effect on E plc's contribution would be: A a decrease of 2% B an increase of 5% C an increase of 10% D an increase of 25% E an increase of 66%.