Ndungula Ltd produces a single product. The company's estimated net profit for the coming year is as follows: Sales N$750 000 Less: variable costs N$352 500 Contribution N$397 500 Less: Fixed costs N$225 000 Net profit N$172 000 If the unit selling price and the unit variable cost each increase by 5%, What effect would this have on the contribution margin ratio? Select one: a. It's not possible to calculate contribution margin ratio from the above information. b. The contribution margin ratio would not c. The contribution margin ration would increase by 5%. d. All statements are correct. e. The contribution margin ration would decrease by 5%