What should the SysOps administrator do to meet this requirement?

Explanations:

Setting the DisableRollback parameter to False would mean that rollback is enabled, which would result in deleting all resources created by CloudFormation if the stack creation fails. This does not meet the requirement of preserving successfully created resources.

Setting the OnFailure parameter to DO_NOTHING during stack creation will ensure that if the stack creation fails, CloudFormation does not automatically roll back the stack, thus preserving any resources that were successfully created prior to the failure. This meets the requirement.

Specifying a rollback configuration with a rollback trigger of DO_NOTHING does not directly apply in CloudFormation; instead, the OnFailure parameter is used to determine behavior on failure. This option does not effectively preserve resources as required.

Setting the OnFailure parameter to ROLLBACK would result in all resources created by CloudFormation being deleted if the stack creation fails. This does not meet the requirement to preserve successfully created resources.