80% will be locked for two years in a smart contract that will buy back BNT for 0.01 ETH (the initial price) whenever it is available, according to its calculated price. The purchased BNT will be added to the Foundation’s long-term budget, and after a 2-year period, any remaining ETH will be allocated pro-rata according to the “Use of Proceeds” chart in our Token Creation Terms.

How this contract will work? How it can purchase BTN when price will be on 0.01ETH? i've came across 3 ideas but i'm not really sure witch one is correct.

1)I mean how is possible for the smartcontract buy back BNT at market price of 0.01ETH without passing through exchanges, buying through exchanges means this will be a smartcontract that can interact with Exchanges' API to work and make an automatic buy when that price is reached.
2)It will be a simply contract that interacts with the seller through wallets, meaning when BTN price on exchanges will hit 0.01ETH you just send your BTN from your wallet to the contract to recive back ETH.
3)The smartcontract will be in Bankor platform itself named like BTNETH contract, but that would mean each token sent back to the platform will be burned as ETH is sent back to the seller meaning less BTN in circulation could drive the BTN price up, cause offer and demand.

Can someone explain this part, because i can't really understand how it works.