Concept:Xerophytes are plants adapted to dry habitats, so their main challenge is water scarcity.
Explanation:Xerophytes grow in arid or desert environments where rainfall is very low.
As a result, the primary problem they face is insufficient water availability.
They develop special adaptations, such as thick cuticles, sunken stomata, and water-storing tissues, to cope with this shortage.
However, the fundamental issue remains the lack of adequate water.
Answer:C. lack of adequate water