The correct answer is A.
An audit trail is a feature of data processing systems that allows for the study of data as processed from step to step; and auditor can then trace all transactions that affect an account. It is a record of all the steps involved in processing a transaction, from the initial entry to the final output. This allows auditors to verify the accuracy and completeness of the data, and to identify any errors or fraud.
Option B is incorrect. A data item is a single piece of information, such as a customer’s name or address. It is not a feature of data processing systems.
Option C is incorrect. Two or more data items handled as a unit is called a record. It is not a feature of data processing systems.
Option D is incorrect. Only option A is correct.
Option E is incorrect. Option A is the correct answer.