Which statement most adequately describes the productivity of trade relative to the productivity of agriculture and manufacturing?

A) Trade is essential in an economy once agriculture and manufacturing have developed, even though it is not productive.
B) Trade is less productive than agriculture or manufacturing.
C) The word productive must be applied to agriculture or manufacturing in the same way it is applied to trade.
D) Trade is productive only insofar as it distributes newly produced agricultural or manufactured goods.
E) Trade is rarely productive because it almost never increases the quantity of goods in the economy.

C