The first one. The use of irrigation.
Answer:
Around the world the most significant restriction on access to potable water is money. While access to raw water sources, clean or otherwise, is important, the purification process itself is expensive. Once water has been rendered potable, it is important that it be delivered without reintroducing contamination.
The continent's southernmost point is incorrectly often said to be Cape Horn, but Águila Islet of the Diego Ramirez Islands is actually the southernmost point.