假设有scores表的设计如下：StudentID（学生编号）,Class（班级），CourseID（课程编号），Score（分数）
(2)一个查询语句执行后显示的结果为：1 班 80；2 班 75；3 班 82，则最有可能的查询语句是
A. SELECT AVG(Score) FROM scores WHERE class<=3
B. SELECT class,AVG(score) FROM scores WHERE class<=3 GROUP BY class
C. SELECT class,AVG(score) FROM scores WHERE class<=3 order by class
D. SELECT class,AVG(score) FROM scores HAVING class <=3 GROUP BY class
