以下（      ）语句可查询选修了三门以上成绩在80分以上课程的学生学号。
A、select  sno 
from sc
where  grade>80
group by sno
having count(cno)>3
B、select  sno 
from sc
where  grade>80
group by sno
having count(*)>3
C、select  sno 
from sc
where  grade>80  and  count(*)>3
group by sno
D、
select  sno 
from sc
where  grade>80
group by sno
having count(sno)>3