设有关系模式：student(sno，sname，age，dept)，现利用命令： CREATE VIEW stu AS SELECT*FROM student WHERE dept= cs WITH CHECK OPTION创建了一个视图。则以下SQL命令中能正确执行的是( )。
A．UPDATE stu SET dept="maths"
B．UPDATE stu SET dept="maths" WHERE age＞=20
C．INSERT INTO stu VALUES("2004001","John",30,"cs")
D．INSERT INTO stu VALUES("2004001","John",50,"maths")