Concept:Crop rotation is the practice of growing different crops sequentially on the same land to maintain soil fertility without leaving land fallow.Explanation:Shifting cultivation depends on moving to new land and leaving old land fallow.Crop rotation allows a wide range of crops to be grown on the same land in successive seasons, which prevents soil nutrient depletion and reduces the need for fallowing.Mixed cropping involves growing different crops together on the same plot at the same time, but it is not specifically about avoiding fallowing.Intensive cultivation focuses on high yields from small land, often with heavy inputs, not necessarily without fallowing.Answer:B. crop rotation