请教一道题目！

kernland imposes a high tariff on the export of unprocessed cashew nuts in order to ensure that the nuts are sold to domestic processing plants. if the tariff were lifted and unprocessed cashews were sold at world market prices, more farmers could profit by growing cahsews. however, since all the processiong plants are in urban area, removing the tariff would seriously hamper the government's effort to reduce urban unemployment over the next five years.

which of the following, if true, most seriously weakens the argument？

a. some of the by-products of processing cashews are used for manufacturing paints and plastices.

b. other countries in which cahsews are processed subsidize their processiong plants.

c. more people in Kernland are engaged in farming cahsews than in processing them.

d. buying unprocessed chasews at lower than world market prices enables canshew processors in Kernland to sell processed nuts at competitive prices.

e. a lack of profitable crops is driving and increasing number of small farmers in Kernland off their land and into the cities.

答案是e.但是为什么呢？好困惑。。。

The conclusion suggests that the tariff should NOT be removed. However, if not removed the tariff, more farmers could NOT profit by growing cashews, increasing the number of growers in Kernland off their land and into the cities. E clearly weakens the argument.