Option (B) is correct because mixed farming does not follow monoculture. Monoculture is the production of single crop or raising of single livestock. Mixed farming involves the growing of crops as well as the raising of livestock.

Option (A) is not correct because dairy farming is monoculture. It is a type of agriculture for production of milk.

Option (C) is not correct because plantation agriculture is the cultivation of cash crops.

Option (D) is not correct because commercial grain farming is an extensive and mechanised form of agriculture in which we mainly cultivate grain.