As Kelly anticipated his retirement from teaching at Kansas University he decided he needed an additional source of income and started a real estate firm that specializes in the leasing, maintenance, and subrental of apartment buildings. Kelly has hired a number of employees to carry out the day to day operations. Employees negotiate the long-term leases of the apartment buildings from their owners, arrange to have them maintained through a series of maintenance contracts, and negotiate/enforce subrental contracts with individual tenants. Usually, the same employee handles all business for a given building throughout its life with the firm (typically 1-5 years), but this sometimes changes because of reassignment or turnover. Employees are paid on a complicated formula that accounts for tenant satisfaction, contractor performance and other factors, so it is important that their participation in past leases, maintenance contracts, and subrentals is accounted for. Owners for buildings are identified by a combination of their name and address while contractors are given a unique ID#. Tenants are identified by social security numbers (SSN). Kelly runs background checks on employees, contractors, and potential lessors, so he adds them to the database as soon as they are cleared. Tenant information is obtained at contract signing time. Building and apartment information is noted when a lease is signed. Subrental contracts can include more than one person; however, one tenant is designated as the prime renter who is legally responsible for final settlements. Tenants are allowed to rent just one apartment at a time. Maintenance contracts note both the buildings and set of apartments covered, but subrental contracts just single out the particular apartment for the contract. Buildings are identified by their address, while apartments are identified by a combination of their building address and apartment number. Apartments range from 1 to 3 bedrooms. Leases cover just one building and when they expire a new lease is written if the parties on both sides want to continue the relationship. Subrental contracts last one year while maintenance contracts last from two months to three years. The set of lessors, contractors, and tenants do not overlap, nor are employees allowed to become any of these parties. Required: Using the narrative description above and the attribute list on the following page develop a conceptual model using UML with classes, associations, and multiplicities specified. Convert your conceptual model into a set of minimal relational database tables. Be sure to identify primary and foreign keys in the tables. You may use the abbreviations (in parentheses) in your tables to save writing time. Do not add any attributes.