Scanning for ( threat`s etc ... ) in `Safe Mode`

a): When entering ` Safe Mode `my screen gives me a choice of

 Administrator or ( my user name ), which to use ?

 

b): Which is better for scanning of threat`s ?

 

c): Why, when a NIS2009 Full System Scan ( in `Safe Mode` ) is performed,

there is no record of it in Security History ( after reBoot ) ?