You need to modify the STUDENTS table to add a primary key on the STUDENT_ID column. The table is currently empty. Which statement accomplishes this task?
ALTER TABLE students ADD PRIMARY KEY student_id;
ALTER TABLE students ADD CONSTRAINT PRIMARY KEY (student_id);
ALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY student_id;
ALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY
ALTER TABLE studentsMODIFY CONSTRAINT stud_id_pk PRIMARY KEY