In performing a cost analysis of a queuing system, the waiting time cost 1Cw2 is sometimes based on the time in the queue and sometimes based on the time in the system. The waiting cost should be based on time in the system for which of the following situations?

a. Waiting in line to ride an amusement park ride

b. Waiting to discuss a medical problem with a doctor

c. Waiting for a picture and an autograph from a rock star

d. Waiting for a computer to be fixed so it can be placed back in service