1. [15 Points ] Consider the following information about a database (DB) application that stores data about employees E and the departments D they work in, employee's immediate supervisor S, and the subordinates of S (employees working under S ). The information on employees E include employee's name (EName), ID (EID), SIN, date of birth (DoB), and the department ID (DID) in which an employee works. For each department, the database records its location and manager. The database includes also information about the supervisor-subordinate relationships. (a) Use an E/R diagram to present the conceptual database design of this application. (b) Convert the diagram in (a) into a relational model and show the result. (c) For each relation schema, in (b), identify the key attribute(s), and alternate keys, if any. State any reasonable assumptions made to justify your answer in (c)