Sunken stomata are present in:

Explanation

Sunken stomata are a characteristic adaptation found in xerophytes, which are plants adapted to dry, arid environments. This adaptation helps reduce water loss by protecting the stomata from direct exposure to the air, thereby minimizing transpiration. Hydrophytes, on the other hand, have adaptations suitable for water-rich environments and do not need to conserve water in the same way. Mesophytes live in environments with moderate water supply and do not have sunken stomata. Therefore, the correct answer is xerophytes.