You are trying to decide between two mobile phone carriers. Carrier A requires you to pay $210 for the phone and then monthly charges of $54 for 12 months. Carrier B wants you to pay $85 for the phone and monthly charges of $68 for 12 months. Assume you will keep replacing the phone after your contract expires. Your cost of capital is 4.4% Based on cost alone, which carrier should you choose? a or b?