Final answer:
A 'key or identifier attribute' uniquely identifies an object in contexts such as databases. Examples include Social Security Numbers or primary keys. Other options listed are not standard terms for this concept.
Step-by-step explanation:
An attribute whose value uniquely identifies an object is called a key or identifier attribute. In database management systems such as SQL, an identifier or key attribute is crucial for establishing relationships between different tables and ensures that each record within a table can be precisely pinpointed without confusion.
For example, the Social Security Number (SSN) in a database of individuals could serve as a key attribute since it is unique to each person. Another common example of a unique identifier is the primary key in a database, which is used to identify each record uniquely.
It is important to distinguish a key attribute from other types of attributes that might have constraints but do not necessarily ensure uniqueness by themselves, such as a 'partially unique attribute' which might be unique combined with another attribute, but not solely. 'Secure attribute' and 'locking attribute' are not standard terms used in this context.