假定学生关系是S(SNo,SName,Sex,Age)，课程关系是C(CNo,CName,Teacher)，学生选课关系是SC(SNo,CNo,Grade)。要查找选修4门以上(含4门)课程的学生总成绩(不统计不及格的课程)，只输出学生学号和总成绩，正确的SQL语句是()
ASELECT Sno,SUM(Grade) FROM SC WHERE Grade>=60 GROUP BY Sno HAVINGCOUNT(*)>=4
BSELECT Sno,COUNT(*),SUM(Grade) FROM SC GROUP BY Sno HAVING Grade>=60 andC OUNT(*)>=4
CSELECT Sno,COUNT(*),SUM(Grade)FROM SC WHERE Grade>=60 GROUPBY Sno HAVING COUNT(*)>=4
DSELECT Sno,SUM(Grade)FROM SC WHERE Grade>=60 and COUNT(*)>=4 GROUP BY Sno