4. Consider the following schemas for a course registration system: StudentGNumber, firstName, lastName, streeet Addres Co state, zipcode) umber, year, semester, courseTit s, city, courseNumber, sectionN le, hours, instructor) RegisteringForCourse( iNumber, courseld a) In the relation(able) Course, do you find another key among the aributes? If you do, list the attributes of the key you found. (7 pts) b).Do you see any table that implements a relationship? If you do, describe how that table(representing a relationship) relates other tables(entities)? (8 pts) c). Write a SQL statement that will return all the courses that all the students take. The result set should have the attributes: jNumber, firstName, lastName, course Number, section Number, year, and semester. Also write a relational algebra expression to do the same. (10 pts)