Which of the following situations describes a linear relationship?
A.During the hour before closing time, the number of customers at a coffee shop decreases by one-fifth every ten minutes.
B.The total cost of a taxi fare increases by $0.50 for each mile driven.
C.Each month, the amount of an unpaid parking ticket doubles.
D.The annual amount of car insurance decreases by 5% for every year of having a good driving record.