All of the Following Are True About Storing a One-To-One

All of the following are true about storing a one-to-one binary relationship in a relational database, except _____.

A) an additional relation must be added to the database
B) two additional relations must be added to the database
C) the primary key of one of the relations in placed in the other relation as a foreign key
D) the two relations involved in the one-to-one relationship can be combined into one relation
E) a particular value of the primary key of one relation is associated with exactly one value of the primary key of the other relation (or possibly with none)