Answer completely and carefully based on web services for thumbs up.

We want to design a RESTful API for a car rental business. The business owns a number of cars of different sizes. There are three size groups for cars called Group A (for small cars), Group B (for medium cars), and Group C (for large cars). Each car group has a specific per-day rental price. A customer can book a car online by specifying the car's size group, the rental start date, and the rental end date. In return the customer gets a unique booking number. We are assuming that there is only one branch for this business in one location, and that the customer can only pick up and return a car to this location. We are also assuming that the customer does not have to pay online to book a car (payment is made in person at the branch when the car is picked up). You do not need to consider payment details and procedures for this exercise. No logging in or authentication is required for any of the services. Customers do not need to provide their details (such as name or address) to make a booking. a) Design a database model for this business, by specifying: i. all required database tables ii. the essential fields of each table iii. and the relationships between the tables