Repeatable Read provides highest data integrity as it holds page and lock the rows until a COMMIT point.

In the context of DB2 or any relational database management system (RDBMS), the highest isolation level that provides the highest data integrity is typically considered to be “Serializable.”

Isolation levels define the visibility of changes made by one transaction to other concurrent transactions. The Serializable isolation level ensures that transactions are executed in such a way that the outcome is as if transactions were executed serially, one after the other, without any interleaved execution.

So, if the question is about the isolation level that provides the highest data integrity, the correct answer would be Serializable.