When said commissioners, in their discretion, decide to lease said claims or properties as provided in RCW 78.16.010, they shall enter an order to that effect upon their records and shall fix the duration and terms and conditions of said lease, and in case an option to purchase is given shall fix the purchase price, which shall not be less than the total amount of the taxes, interest and penalties due at the time the property was acquired by the county, and may provide that any royalties paid shall apply and be credited on the purchase price, and said lease or lease and option shall be signed and executed on behalf of said county by said commissioners, or a majority of them.