How to find out which users are logged on to sap hana last week

Dear Friends,

This is one of the certification question in SAP HANA. Could anyone please help if you know the answer?

You need to find out which users are logged on to sap hana last week (1 right answer)

               a.       Audit log

               b.      The name server_history.trc file

               c.       The index server_alert.trc file

               d.      Entries in M_connection

Thanks in advance,

Best Regards,

KV