$ cat C
grape
apricot
cherry

$ perl -e 'open F,$ARGV[0] or die;shift;my %set = map {$_ => 1 } <>; for (<F>) {print unless $set{$_}};' A B C
apple
carrot

$ perl -e 'open F,$ARGV[0] or die;shift;my %set = map {$_ => 1 } <>; for (<F>) {print if $set{$_}};' A B C
cherry
lime