: Seventeen points are placed in the plane with no two on the same horizontal line and no two on the same vertical line. Prove that there must be five points that can be joined to give an upward path (as viewed from left to right) or five points that can be joined to give a downward path.

Commercial agriculture consists of raising food for trade and profit, while subsistence agriculture focuses on -- a. providing the basic needs of the farmer's family b. providing the basic needs of the neighboring communities c. creating more arable land for future use d. obtaining subsidies from governments and corporations