Pete Pella is chair of the local possum association, which maintains a database of all possums within the community. One table will store the name, birth date, and other characteristics of all of the possums that have been registered. Each possum is uniquely identified by a registration number. A second table will contain data that link each possum to its male and female parents by means of their registration numbers. The primary key in the second table is

name.

birth date.

the same as the primary key in the first table.

a combination of primary keys in the first table.