A downstream application wants to have all the entries in the mobile column of the customers table for auditing purposes. The following streaming query has been set up by the data engineer: spark . readStream . format ( 'delta' ) . option ( 'readChangeFeed' , 'true' ) . table ( 'customers' ) . select ( 'mobile' ) . writeStream . format ( 'delta' ) . option ( 'checkpointLocation' , '/tmp/customers/_checkpoints/' ) . table (‘ mobiles ') Which of the following updates should be made to the query to restrict duplicate entries in the mobiles table?