What distinguishes a primary key from a foreign key?

The distinction between a primary key and a foreign key is fundamental in relational database design. A primary key uniquely identifies each record within its own table, ensuring that no two records can have the same value for that key. This uniqueness is crucial for maintaining data integrity, as it allows each record to be distinctly referenced and accessed without confusion.

On the other hand, a foreign key serves a different purpose: it creates a relationship between two tables. A foreign key in one table points to a primary key in another table, effectively linking the two tables together. This relationship enables the database to enforce referential integrity, ensuring that the foreign key value corresponds to a valid entry in the referenced table.

This clear separation of roles between primary and foreign keys is what makes option B the correct choice. It accurately describes the function of each key: the primary key uniquely identifies records within its own table, while the foreign key establishes connections to primary keys in other tables.