Final answer:
A composite key is the correct answer, as it uses multiple fields to uniquely identify a record in a database table.option c.
Step-by-step explanation:
The constraint that uses multiple fields as a primary key is C. composite key. A composite key is a type of database key that consists of two or more columns which together uniquely identify a record in a table. It is used when no single column can serve as a unique identifier and a combination of columns is required to guarantee row uniqueness.
On the other hand, A. foreign key refers to a column or group of columns in a table that uniquely identifies a row in another table, typically forming a link between the two tables. B. unique is a constraint that ensures all values in a column or a set of columns are distinct. Lastly, D. check is a constraint that limits the values that can be placed in a column based on a Boolean expression.
The constraint that uses multiple fields as a primary key is called a composite key.
A composite key is a key that is composed of two or more attributes, or fields, that together uniquely identify a record in a database table. In other words, it uses a combination of multiple fields to create a unique identifier for each record.
For example, in a database table for student records, a composite key could be a combination of the student's first name, last name, and student ID. This combination of fields would ensure that each student record is unique and can be easily identified.