Which type of keys links to multiple rows in another entity?

The correct choice highlights that foreign keys are essential for establishing relationships between tables in a relational database. When a foreign key is defined in one table, it corresponds to a primary key in another table. This allows multiple records in the table containing the foreign key to reference a single record in the table with the primary key, effectively linking these multiple rows in one entity to a single unique row in another entity.

Foreign keys are fundamental to maintaining referential integrity, enabling complex queries and operations that involve relationships between different datasets. This makes it possible to model real-world relationships within the data structure, such as how a single customer might have multiple orders.

Other types of keys, such as unique keys, serve different purposes. Unique keys ensure that each value in a column is distinct but do not create multi-row relationships like foreign keys do. Type keys and array keys are not standard concepts used in relational databases and do not play a role in linking multiple rows across different entities.