We are given the following relational database schema for a database that keeps track of student enrollment in courses and the books adopted for each course. STUDENT COURSE Course# Cname Dept Ssn Name Major Bdate BOOK ADOPTION Course# Semester Book.ISBN ENROLL Ssn Course# Semester Grade TEXTBOOK ISBN Title Publisher Author a. Consider the COURSE relation. Assuming that names of courses are unique, list all the superkeys, keys, candidate keys, and select a primary key. i. Superkeys: ii. Keys: iii. Candidate keys: iv. Primary key: b. Select and underline the primary key in each relation (in the schema above). Justify your choices and state any assumption that you make. c. Circle all foreign keys and specify the referential integrity constraints by drawing directed arcs on the schema diagram on the previous page. d. Draw an ER diagram that would correspond to the relational schema above. (Drawing by hand is OK.)