检索选修四门以上课程的学生总成绩，并要求按总成绩的降序排列出来。正确的SELECT语句是（）。

A.SELECT SNO, SUM（GRADE）FROM SC GROUP BY SNO ORDER BY 2 DESC HAVING COUNT（*）>= 4;

B.SELECT SNO, SUM（GRADE）FROM SC GROUP BY SNO HAVING COUNT（*）>=4 ORDER BY 2 DESC;

C.SELECT SNO, SUM（GRADE）FROM SC HAVING COUNT（*）>=4 GROUP BY SNO ORDER BY 2 DESC;

D.SELECT SNO, SUM（GRADE）FROM SC ORDER BY 2 DESC GROUP BY SNO HAVING COUNT（*）>=4;

正确答案：SELECT SNO, SUM（GRADE）FROM SC GROUP BY SNO HAVING COUNT（*）>=4 ORDER BY 2 DESC;