单项选择题

设有一个关系Student(学号,姓名,系名,课程号,成绩),查询至少选修了四门课程的学生学号、姓名及平时成绩的SELECT语句应该是:
SELECT学号,姓名,AVG(成绩) AS平均成绩
FROM Student
GROUP BY (1)
HAVING (2)

A.部门号where sum(销售量)>1000
B.部门号having sum(销售量)>1000
C.商品号where sum(销售量)>100
D.商品号having sum(销售量)>1000