检索选修课程“C2”的学生中成绩最高的学生的学号。正确的SELECT语句是()。A.SELECT SNO FORM. SCW
A.SELECT SNO FORM. SCWHERE CNO='C2' AND GRADE >= (SELECT GRADE FORM. SC WHERE CNO='C2');
B.SELECT SNO FORM. SCWHERE CNO='C2' AND GRADE IN (SELECT GRADE FORM. SC WHERE CNO='C2');
C.SELECT SNO FORM. SCWHERE CNO='C2' AND GRADE NOT IN (SELECT GRADE FORM. SC WHERE CNO='C2');
D.SELECT SNO FORM. SCWHERE CNO='C2' AND GRADE >= ALL (SELECT GRADE FORM. SC WHERE CNO='C2');