Write a linear cost function for the situation. Identify all variables used. A parking garage charges 9 dollars plus 25 cents per half-hour. Identify all variables used. Choose the correct answer below. OA. C(x) represents the number of half-hours the parking garage was used after pay x dollars. OB. C(x) represents the number of hours the parking garage was used after paying x llars. Wars represents the cost for using the parking garage for x half-hours. OD. C(x) represents the cost for parking x cars in the parking garage.