The seller determines this. You could try to negotiate if you like. Be warned though. Very, very few lease options ever turn into closed sales. Landlords love the arrangement. No close? No deposit return!
Many states, including Tennessee have withdrawn lease-purchase contracts from the Realtor arsenal of available forms. They frown on the legalities of the arrangement too. Personally I consult my prospects to rent on the cheap for awhile and to save up their own down-payment. FHA only requires 3.5% down and 580 midscore.