Consider the following problem description for an online reservation system for a bus company.

The bus company includes several buses and realizes trips to different cities. Each bus is identified by its plate number and a separately assigned bus number. The trips are based on a predefined schedule and stop at predefined bus stations. Each bus can have only one trip per day. Each bus includes a driver and one hostess.

Passenger and bus company administrator can view seats at any time. Seats can be reserved by passenger on the web site of the bus company. The passenger has the option to directly pay for the seat through the website. In that case, the seat cannot be cancelled (neither by the passenger nor by the bus company administrator). If the passenger has not paid for the seat, the bus company administrator can cancel the seat if the passenger does not show up one hour before the trip. When the reservation is cancelled, the seat will become free and can be sold to another passenger. Both the passenger and the bus company administrator must authenticate themselves for performing operations with the system except view seats.

a) Draw a use case diagram for describing the functional requirements of the above system.

(9 marks)