Question about Amulet of Natural Armor

I have a player that wants to craft an Amulet of Natural Armor +2. It says that it provides an enhancement bonus to Natural Armor. He doesn't currently have a Natural Armor bonus. Does the Amulet work at all? I'm of 2 minds about this.

1. He has no natural armor, so you can't enhance what's not there. It would be like adding studs onto leather to make studded leather. If he's not wearing leather, you can't add the studs, so if he's not 'wearing' natural armor, you can't enhance it.

OR

2. Everyone has Natural Armor +0 (or more) so it would work to enhance the 0 to +2 as it would thicken his skin.

Which one is correct?

Number 2 is correct.

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The enhancement bonus provided by barkskin stacks with the target's natural armor bonus, but not with other enhancement bonuses to natural armor. A creature without natural armor has an effective natural armor bonus of +0.

A creature without natural armour has an effective natural armour bonus of +0.