A database needs to be developed that keeps track of PhD students: For each student store the name and matriculation number. Matriculation numbers are unique. Each student has exactly one address. An address consists of street, town and post code, and is uniquely identified by this information. For each lecturer store the name, staff ID and office number. Staff ID's are unique. Each student has exactly one supervisor. A staff member may supervise a number of students. The date when supervision began also needs to be stored. For each research topic store the title and a short description. Titles are unique. Each student can be supervised in only one research topic, though topics that are currently not assigned also need to be stored in the database. Tasks: a) Design an entity relationship diagram that covers the requirements above. Do not forget to include cardinality and participation constraints. b) Based on the ER-diagram from above, develop a relational database schema. List tables with their attributes. Identify keys and foreign keys.