众所周知，GROUP BY会对结果集进行排序。进而消耗较大的资源开销。
在MySQL 5.7版本中，以下哪些写法能避免文件排序？

A select col1,sum(col2) from table group by col1 asc;
B select col1,sum(col2) from table group by col1 order by 1;
C select col1,sum(col2) from table group by col1 order by 1=1;
D select col1,sum(col2) from table group by col1 order by rand();
E select col1,sum(col2) from table group by col1 desc;
F select col1,sum(col2) from table group by col1 order by null;