在SQL Server中，STUDENT_GRADES表有这些列：
STUDENT_ID INT
GPA FLOAT
以下哪项语句能找到每学期最高的平均学分绩点 (GPA)？( )
SELECT MAX(gpa) FROM student_grades WHERE gpa IS NOT NULL
SELECT (gpa) FROM student_grades GROUP BY semester_end WHERE gpa IS NOT NULL
SELECT MAX(gpa) FROM student_grades WHERE gpa IS NOT NULL GROUP BY semester_end
SELECT MAX(gpa) GROUP BY semester_end WHERE gpa IS NOT NULL FROM student_grades
SELECT MAX(gpa) FROM student_grades GROUP BY semester_end WHERE gpa IS NOT NULL
