Determine the correct primary key for the relation Student_info.
| Student_info | |||
| Student_id | Student_name | course_id | course_name |
| 1 | Ramu | c1 | DBMS |
| 2 | Ravi | c1 | DBMS |
| 3 | Raju | c2 | CN |
| 1 | Ramu | c2 | CN |
| 4 | Rohan | c2 | DBMS |
1
Student_id
2
Student_id, Student_name
3
Student_id, Course_id
4
Course_id, course_name