In Workday, custom validations are evaluated based on business process context, including the event type that triggered the process. The Request One-Time Payment and Request One-Time Payment for Self are separate event types, even though they share similar functionality.

To prevent existing validations from running for employee self-service requests, administrators must explicitly exclude the self-service event type within the validation logic. This is done using the Maintain Custom Validations task, where conditions can be added to evaluate the One-Time Payment Event for Self field.

Security changes are not appropriate because the requirement is to allow the process but exclude validations. Optional field configuration does not control validation execution. Creating additional validations does not stop existing ones from firing.

By excluding the One-Time Payment Event for Self event type within the validation, Workday ensures validations continue to apply to administrator-initiated requests but not to employee self-service requests.

Therefore, option C is the correct and Workday-supported solution.