The common fields used in a relationship between tables are called :

Key Fields

The correct answer is Option (3) - Key Fields.

The common fields used in a relationship between tables are called key fields. Key fields are used to link records in one table to related records in another table. There are two types of key fields:
Primary key: A primary key is a unique identifier for each record in a table.
Foreign key: A foreign key is a field in one table that references the primary key in another table.