【单选题】统计图书信息表中每个出版社图书的平均价格。能得到正确结果的SELECT语句是 A: A、select pubname,AVG(price) from bookinfo order by puname B: select pubname,AVG(price) from bookinfo group by pubname C: select pubname,price from bookinfo D: select pubname,AVG(price) from bookinfo