The correct answer is tables.
Referential integrity is a set of rules that ensures that data in one table is consistent with data in another table. It is enforced by the database management system (DBMS) and prevents data from being entered into a table that would violate the rules.
For example, if you have a table of customers and a table of orders, referential integrity would prevent you from adding an order to the orders table if the customer does not exist in the customers table.
Referential integrity can be enforced if both tables belong to the same database. This is because the DBMS can then track the relationships between the tables and ensure that they are consistent.
Queries, fields, and records are all elements of a database table, but they do not have the same relationship to each other as tables do. Queries are used to select data from one or more tables, fields are the columns in a table, and records are the rows in a table.
Therefore, the only option that ensures that referential integrity can be enforced is tables.