During a foreign trip, you choose a $15/day cell phone plan. The $15 fee per day is deducted each day, no matter whether you use the service or not. Also, the plan allows you 100 free minutes and one GB of data per day. Each additional usage beyond 100 minutes would cost you $0.5 per minute. Suppose you use 53 minutes in one day while staying within 1 GB data limit. How much is your marginal cost? $0.00 $1.5 $2.5 $12.5