COURSE subj code course number course name course description credits - subj code and course number is always required for all courses, and change is rare - course name is always required for all courses, but the change is more frequent than course number to reflect current understanding. - course description is always long text description and change is more frequent than course name to reflect updates made to the course content. Based on the above information, select all choices that meet the necessary criteria to serve as a primary key. subj code and course number together course number course name subj code course description credits