Concept:Winnowing separates lighter chaff from heavier grains using wind or air current.Explanation:Cereals like rice, maize, and millet are harvested along with husks and chaff.After threshing, winnowing is used to clean these grains.The process is not typically needed for fruits, tubers, or vegetables.Therefore, cereals are the group that require winnowing during processing.Answer:B. Cereals