What type of database software integrity service guarantees that tuples are uniquely identified by primary key values?

A.
Concurrent integrity

B.
Referential integrity

C.
Entity integrity

D.
Semantic integrity

Explanation:
C: Entity integrity guarantees that the tuples are uniquely identified by primary key values. A tuple is a row in a two-dimensional database. A primary key is a value in the
corresponding column that makes each row unique. For the sake of entity integrity, every tuple must contain one primary key. If a tuple does not have a primary key, it cannot be
referenced by the database.
A is incorrect because concurrent integrity is not a database software formal term. This is a distracter answer. There are three main types of integrity services: semantic, referential,
and entity. Concurrency refers to a piece of software being accessed by multiple users and/or applications at the same time. If controls are not in place, two users can access and
modify the same data simultaneously.
B is incorrect because referential integrity refers to all foreign keys referencing existing primary keys. There should be a mechanism in place that ensures that no foreign key
contains a reference to a primary key of a nonexisting record or a null value. This type of integrity control ensures that the relationships between the different tables are working and
can properly communicate to each other.
D is incorrect because a semantic integrity mechanism ensures that structural and semantic rules of a database are enforced. These rules pertain to data types, logical values,
uniqueness constraints, and operations that could adversely affect the structure of the database.