You want the user sarah to help you with backups to an external drive. What is wrong with the configuration below?

Cmnd$\_$Alias BACKUP $=$ rsync $-$av $/$etc $/$media$/$extdrive

sarah ALL$=$BACKUP

a$.$ Nothing is wrong

b$.$ The user would be able to backup anything to any destination directory

c$.$ The user would be able to execute as root any binary named rsync in the working directory

d$.$ The user would be able to change the $/$etc$/$sudoers configuration