Final answer:
An audit trail is used to trace business events aggregated into account balances back to their individual occurrences, ensuring the accuracy and integrity of financial data.
Step-by-step explanation:
Tracing back to individual business events that have been aggregated into account balances is done by means of a C) Audit trail. An audit trail consists of a series of documents that provide a historical record of transactions, allowing an examiner to understand and trace the financial data from the summaries on the financial statements back to the original business activities. This process is crucial in verifying the accuracy and integrity of the financial information and ensuring that all entries are both authorized and correctly recorded, thus having a fundamental role in internal control procedures, financial analysis, and legal forensic activities.