现有书目表book,包含字段:价格price(float),类别type(varchar);现在查询各个类别的平均价格,类别名称,以下语句正确的是? ()
A.select avg(price),type from book group by type
B.select count(price),type from book group by price
C.select avg(price),type from book group by price
D.select count(price),type from book group by type