Effective separation of duties in an online environment can BEST be achieved by utilizing:

Appropriate supervision is a compensatory control or a general management practice but does not technically enforce separation of duties in an online system.

Access authorization tables, often implemented as role-based access control (RBAC), provide a technical enforcement mechanism to separate duties by defining and restricting what specific users or roles can do within an application. This ensures that no single individual has conflicting permissions that could lead to fraud or error, directly achieving separation of duties.

Transaction logging provides an audit trail of actions performed but does not prevent unauthorized combinations of duties from being executed.

Written procedure manuals document responsibilities but rely on human adherence and do not technically enforce separation of duties within a system.