The correct answer is - D. All of the above.
The ecosystems of the Andes are very important for multiple reasons. They are managing to keep the air clean in the region around them. The healthy and clean environment helps in the cleanness of the freshwater reserves. Also, since big portion of the Andes are covered with vegetation, it is of big help for preventing the erosion of the soil as it is held tightly. The desertification can not take place. Since the vegetation is taking in big amounts of water, it is helping a lot in the prevention of the floods and landslides. So all in all, the Andes ecosystems are crucial for the well-being of the whole region, and the humans should respect them and protect them as best as they can.
