According to Crusoe the characteristic that mutineer had that made them unsuitable masters was B) Cruelty.
When Crusoe sees the mutineers landing he watches from where he is hiding how they treat the three men they hold as prisoners. They are about to kill them and they have no mercy for them. Afterward, Crusoe learns from one of the prisoners, who is the captain of the ship, that two of those men were the ones who started the mutiny and that they were villains.
