Which of the following is a method to protect information integrity within a system?

Data integrity is a key aspect of information security that ensures data remains accurate, consistent, and unaltered throughout its lifecycle. Among the methodologies listed, data encryption specifically serves to protect information integrity by safeguarding the data from unauthorized access and tampering.

When data is encrypted, it is transformed into a format that can only be read or processed by someone who has the correct decryption key. This prevents unauthorized users from modifying the original data, thus preserving its integrity. If an unauthorized user attempts to alter encrypted data, they will not be able to do so without detection since any unauthorized changes would likely result in the encryption becoming invalid when the data is decrypted.

Data backup, firewalls, and access control also play significant roles in a comprehensive information security strategy, but their primary functions differ from specifically ensuring data integrity. Backups focus on data recovery, firewalls serve to protect against unauthorized access, and access control measures determine who can view or manipulate data, but they do not inherently prevent alterations to the data itself in the same direct manner that encryption does.