单选题 The passage is primarily concerned with discussing

• (A) how anthropologists ought to explain the origins of the trade relationship between foragers and agriculturalists
• (B) why it is difficult to measure the amount of time necessary for the disappearance of carbohydrate-rich plant species in the rain forest
• (C) why a particular account of the unavailability of carbohydrates to rain forest foragers is inaccurate
• (D) what ought to be included in any account of the effects of forager peoples on rain forest ecology
• (E) what data are most relevant for an accurate account of the relations between rain forest foragers and agriculturalists