The correct answer is: a) Soil erosion and nutrient loss.
Shifting cultivation (Jhum cultivation) is a traditional agricultural practice in which a piece of land is cultivated for a few years and then abandoned for several years to allow the land to regenerate. This practice can lead to soil erosion and nutrient loss, as the land is not left fallow for long enough for the soil to recover.
Soil erosion is the process of soil being removed from the land by wind or water. This can be caused by a number of factors, including deforestation, overgrazing, and agriculture. Soil erosion can lead to a number of problems, including loss of topsoil, which is the most fertile layer of soil, and sedimentation in waterways, which can disrupt ecosystems.
Nutrient loss is the process of nutrients being removed from the soil. This can be caused by a number of factors, including leaching, erosion, and crop removal. Nutrient loss can lead to a number of problems, including reduced crop yields and increased soil acidity.
Increased soil fertility, improved soil structure, and rejuvenation of degraded soils are not the main consequences of shifting cultivation.