The resolution of the board of county commissioners to grant an option to purchase, contract to sell, lease, sell and convey, or donate, as provided, shall be entered by said board upon its journal, and any option to purchase, contract to sell, lease, sale and conveyance, or donation executed pursuant thereto, shall be signed on behalf of the county by the board of county commissioners, or a majority thereof, and shall be acknowledged in the manner prescribed by law.
RCW 36.34.270