The correct answer is: d) All of the above.
Terrace farming is a method of farming that involves creating a series of terraces on a slope. This helps to reduce soil erosion and makes it easier to farm on steep slopes. Afforestation is the planting of trees on land that was previously not forested. This helps to prevent soil erosion and provides a habitat for wildlife. Contour bunding is a method of soil conservation that involves creating a series of low walls across the slope of a field. This helps to trap water and prevent soil erosion.
All of these methods are used in Arunachal Pradesh to conserve soil. Terrace farming is particularly common in the hilly areas of the state, while afforestation is more common in the lower-lying areas. Contour bunding is used in both hilly and lowland areas.
Soil conservation is important in Arunachal Pradesh because the state is prone to soil erosion. Soil erosion can lead to a loss of topsoil, which is the most fertile layer of soil. This can make it difficult to grow crops and can also lead to the loss of biodiversity. Soil conservation measures help to protect the soil and prevent erosion.