Which two statements are true regarding single row functions?

Which two statements are true regarding single row functions? (Choose two.)

A.
They a ccept only a single argument.

B.
They c an be nested only to two levels.

C.
Arguments can only be column values or constants.

D.
They a lways return a single result row for every row of a queried table.

E.
They c an return a data type value different from the one that is referenced.