We are designing a DB system for storing COVID-19 data in the kingdom. The database stores the COVID-19 data for different cities across the kingdom. Where each city has an id, name. Moreover, each city has a number of test centers. Each test center identified by center-id, name, location. Anyone has a suspect with COVID-19 infection he reserves an appointment. For an appointment reservation a person must be registered on the system with his name, Id number, mobile phone number (05x-XXX-XXXX) and nationality. While reserving an appointment you have to enter your id and select day, time and test center closest to you then you will get an auto-generated reservation number. For a given reservation number, we keep track of the test result. A test result can be either (positive or negative). a) Draw an ER diagram of the system indicating any assumptions needed b) Map the ERD to a schema diagram and identify the primary keys and the foreign keys (if any) and the relationships between the tables