Which of the following represents a proportional function? A. the amount of money on a gift card, if the original amount is $200 and $50 is spent once a week for 4 weeks

B. the amount of money charged for a hotel room, if the cost is $86 per day

C. the amount of money that is charged for a cleaning service, if the cost is $25 per visit, plus $15 for each hour of work

D. the savings in a bank account, if $100 is initially deposited and $25 is deposited each week afterwards