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AUM has been retaining about 15 minutes worth of undo. You want to double the retentionperiod， but not at the expense of new transactions failing. You decide to alter the system to set the parameter UNDO_RETENTION=18000. However， AUM still retains only about 15 minutes worth of undo. 
What is the problem？ （） 

A user named Arren is executing this query：  
select table_name，operation，undo_sql 
from 
flashback_transaction_query t， 
（select versions_xid as xid 
from employees versions between scn minvalue and maxvalue 
where employee_id = 123） e 
where t.xid = e.xid；  
When the query runs，he receives an ORA-01031： insufficient privileges error. Since the user owns the employees table，you know that it is not the problem. 
Which of the following SQL statements will correct this problem？（）