Final answer:
A complete set of attributes for a single occurrence of an entity class in a database is called a record, which is a single entry that represents a full unit of information.
Step-by-step explanation:
In a database, a complete set of attributes for a single occurrence of an entity class is called a record. Among the provided options, a key is a unique identifier, a file is a collection of records, and a character is a single alphabetic, numeric, or other symbol. A record, on the other hand, represents a single entry that contains all the relevant data for one instance, such as a person's data in a contact list database including name, phone number, address, etc. These attributes collectively define one complete unit of information.
In a database, a complete set of attributes for a single occurrence of an entity class is called a record. A record represents a single entry or row in a database table and contains all the information related to that particular entity. For example, in a student database, a record would include attributes such as student ID, name, address, and phone number.