课程表结构如下SC(Sno, Cno, Cname, Grade),其中列Cno和Sno的数据类型均为varchar(20),Cname为nvarchar(20),Grade数据类型为smallint。查询门门课程的成绩在80分以上的学生的学号,对应的SQL语句可以是( )。 A. SELECT Sno FROM SC GROUP BY Sno HAVING MIN(Grade)>80; B. SELECT Sno FROM SC GROUP BY Sno HAVING avg(Grade)>80; C. SELECT Sno FROM SC GROUP BY Sno HAVING min(Grade)>80; D. SELECT Sno FROM SC GROUP BY Sno HAVING max(Grade)>80;