A.A subquery can retrieve zero or more rows 
B.Only two subqueries can be placed atone level 
C.A subquery can be used only in SQL query statements 
D.A subquery can appear on either side of a comparison operator 
E.There is no limit on the number of subquery levels in the WHERE clause of a SELECT statement 

A.They accept only a single argument 
B.They can be nested only to two levels 
C.Arguments can only be column values or constants 
D.They always return a single result row for every row of a queried table 
E.They can return a data type value different from the one that is referenced