Which of the following implementation controls specifically addresses the risk that historical financial data transferred from a legacy system contains errors that affect comparative period reporting?
- Training all accounting staff on the new system before data migration.
- Reconciling migrated historical data balances by period to the legacy system's audited financial statements and prior period trial balances. (correct answer)
- Encrypting all historical data during the migration process.
- Archiving the legacy system data in a separate storage location after migration.
Explanation: Reconciling migrated historical data to audited financial statements ensures comparative period data is accurate - directly addressing the risk of historical data errors in the new system. Answer B is correct. Training (A) addresses operational readiness. Encryption (C) addresses security. Archiving (D) addresses retention.