[请教]陈向东逻辑假设习题第47

Exports of United Stateswood pulp will rise considerably during this year. The reason for the rise is that the falling value of the dollar will make it cheaper for paper manufacturers in Japan and Western Europe to buy American wood pulp than to get it from any other source.
Which of the following is an assumption made in drawing the conclusion above?

A.Factory output of paper products in Japan and
Western Europe will increase sharply during this year.

B.The quality of the wood pulp produced in the United States
would be adequate for the purposes of Japanese and Western European paper manufacturers.

C.Paper manufacturers in Japan and Western Europe would prefer to use wood pulp produced in the
United States if cost were not a factor.

D.Demand for paper products made in Japan and
Western Europe will not increase sharply during this year.

E.Production of wood pulp by United States
companies will not increase sharply during this year.

为何C不对呢？ C 不是题中论证的逆否命题吗？