In a database, what is the function of a primary key?

A primary key is a fundamental concept in database design that serves the critical function of identifying unique records within a table. Each record in a database must be uniquely identifiable to ensure that the information stored can be accurately retrieved, updated, or related to other data. The primary key is a single field or a combination of fields that ensures that no two records in the table can be identical, which is vital for maintaining data integrity.

For example, in a database of students, a primary key might be a student ID number. Since each student has a unique ID, this key can distinguish one student from another, allowing for clear and concise data management. The uniqueness of the primary key not only facilitates data retrieval but also supports the relationships between different tables in a relational database, which can enhance overall database functionality.

This understanding enables the creation of efficient queries and maintains referential integrity, making option B the accurate choice in this context.