Final answer:
To mitigate the risk of master data destruction without an ERP system, firms should implement backup and disaster recovery procedures, which provide robust data protection by storing data copies securely and offsite.
Step-by-step explanation:
If a firm does not use an Enterprise Resource Planning (ERP) system, the best way to mitigate the risk of the destruction of master data is to implement backup and disaster recovery procedures.
This approach involves regularly creating copies of data and storing them in a secure location, preferably offsite, to prevent the loss of data in the event of a disaster, system failure, or malicious attack.
Segregation of duties is important for internal controls but does not directly protect data from destruction, and while using multiple master data files may provide a rudimentary form of redundancy, it is not a substitute for a comprehensive backup and disaster recovery plan.