Which of the following regarding the representation of data relationships in a relational database is true? Data should never be used to represent relationships. Relations are documented by using examples containing appropriate data. Only numeric data can be used to represent relationships. Relations are documented by using examples containing primary key and/or foreign key data. Question 12 6.67pts Which of the following is true regarding primary keys in a relational database? Unique primary keys make it possible to identify every row in a table. Any bit of data can be located by referencing the name of the table and the primary key of the row. In certain circumstances, a primary key may contain a null vale. A relation can only have one primary key