The STUDENT_GRADES table has these columns: STUDENT_ID NUMBER(12) SEMESTER_END DATE GPA NUMBER(4,3) Which statement finds the highest grade point average (GPA) per semester?（）

A. SELECT MAX (gpa) FROM student _ grades WHERE gpa IS NOT NULL;

B. SELECT (gpa) FROM student _ grades GROUP BY semester_end WHERE gpa IS NOT NULL;

C. SELECT MAX (gpa) FROM student _ grades WHERE gpa IS NOT NULL GROUP BY semester_end;

D. SELECT MAX (gpa) GROUP BY semester_end WHERE gpa IS NOT NULL FROM student _ grades;

E. SELECT MAX (gpa) FROM student _ grades GROUP BY semester_end WHERE gpa IS NOT NULL;