Please see Rule #7 on the Investigation Rights. It's a small but meaningful edit. Neutral has been added because they might think that they are immune to the "1 choice" scenario, where in fact, they are not.
7. If the choice is only 1, the decision whether the number is an Assassin's or a Detective's or a Neutral's will be done by random. The percentage of it being an assassin's will depend on the ratio of Detectives to Neutrals to Assassins during that time.
Well, it seems i don't have the required cerebral capacities to play to your AG [MENTION=1564]Hor-niichan[/MENTION]... i just hope it isn't the lower level of your puzzles... cause i'm already _@: