Final answer:
In database design, a key attribute is a unique identifier for records, and while designing a relational database, non-key attributes of an entity type do not become key attributes in the relation.
Step-by-step explanation:
The statement that each non-key attribute of the entity type becomes a key attribute of the relation is incorrect in the context of database design, specifically in relational database models. In designing a relational database, each entity is generally represented as a table. The table consists of columns that represent the attributes of the entity. A key attribute, which is often the primary key, is a unique identifier for each record in the table. Non-key attributes are the other attributes that describe properties of the entity but do not uniquely identify the records. When converting an entity type to a relational schema, only the primary key of the entity type becomes the primary key of the relation, and the non-key attributes remain as non-key attributes within the relation.