表sc中存放了多个学生的多门课程的成绩，sno为学号，cno为课程号，grade为成绩。要查询平均分最高的学生学号和平均分，下列（）语句可以实现。
选项：

A:SELECT top 1 sno,avg(grade) FROM sc group by sno order by avg(grade) desc
B:SELECT sno,max(avg(grade)) FROM sc group by sno
C:SELECT sno,max(grade), avg(grade) FROM sc group by sno
D:SELECT sno,max(grade) FROM sc group by sno