Which three statements are true regarding group functions? (Choose three.)
A.
They can be used on columns or expressions.
B.
They can be passed as an argument to another group function.
C.
They can be used only with a SQL statement that has the GROUP BY clause.
D.
They can be used on only one column in the SELECT clause of a SQL statement.
E.
They can be used along with the single-row function in the SELECT clause of a SQL statement.
Explanation:
https://www.safaribooksonline.com/library/view/mastering-oracle-sql/0596006322/ch04.html