B. Generally between 900 and 2000 meters (3000-6500 feet) with plenty of ups and downs. Travelers need to be regular walkers to fully enjoy this experience. It is possible, however, to design "easy and short" three or four day treks with only two to five hours walking per day. 

C. Possibly involving side trips to higher elevations between 900 and 3000 meters (3000 - 10000 feet).

D. Reasonably demanding trekking at altitude up-to 4000 meters (13000 feet) with trips to higher elevations and could include treks away from villages on ill-defined mountain trails. Treks in other areas treks of demanding nature, require all participants to be fit and in excellent health, often in remote alpine areas and sometimes reaching altitudes over 5500 meters (18000 feet) and high pass crossing over.