Final answer:
The sap of the Agave plant is a suitable substitute for fresh water in arid regions due to its water-storing adaptations.
Step-by-step explanation:
The sap of the Agave plant is credited with being a reliable substitute for fresh water in the arid countryside. Agaves are succulents, equipped with adaptations to survive in dry climates. They have a waxy cuticle with sunken stomata to minimize water loss. The Agave plant's ability to store water in its stem, and its use by Pre-Columbian American populations as a source of hydration, make it a valuable resource for individuals in areas lacking fresh water.