Final answer:
The claim that a primary key must be composed of exactly two fields is false; a primary key can be a single field or a composite key of multiple fields.
Step-by-step explanation:
The statement that a primary key is composed of exactly two fields is false. A primary key in a database is a unique identifier for each record in a table and can consist of one or more fields, depending on the table structure and the data it holds. When a primary key consists of two or more fields, it is known as a composite key.
For example, in a school database, a student's record could have a primary key made up of just one field, such as 'StudentID', or it could have a composite key made up of multiple fields like 'SchoolID' and 'StudentID' if students are only unique within each school.