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( )。<br/> A SELECT Sno FROM SC WHERE Cno=’C2’ AND GRADE>=(SELECT GRADE FORM SC WHERE Cno=’C2’) <br/> B SELECT Sno FROM SC WHERE Cno=’C2’ AND GRADE IN (SELECT GRADE FORM SC WHERE Cno=’C2’) <br/> C SELECT Sno FROM SC WHERE Cno=’C2’ AND GRADE NOT IN (SELECT GRADE FORM SC WHERE Cno=’C2’) <br/> D SELECT Sno FROM SC WHERE Cno=’C2’ AND GRADE>=ALL (SELECT GRADE FROM SC WHERE Cno=’C2’)