Actually, the quiz is designed to require the least amount of "zombie" type-ins necessary. The only ones present are necessary to distinguish zombies from each other. For example, Cave Zombie requires the "Zombie" because if you started typing Cave Conehead Zombie it would automatically accept Cave Zombie from only the Cave. In the same example, only typing "Cave Conehead" will be accepted because that is enough to distinguish it from any other zombie. So it goes for most of the rest.