PREP08第一部分75题。。求分析为什么是方案推理？ - ChaseDream

Kernland’s government restricts the export of unprocessed cashew nuts in order to ensure a low-cost supply for domestic processing plants. Though the policy constrains farm income and limits the number of farmers who can profitably grow cashews, the government defends it on the grounds that, since the processing plants are in urban areas, removing the restrictions would hurt efforts to reduce urban unemployment. However, the policy may actually have contributed to urban unemployment, since __________.

这里不是有说 Though the policy constrains farm income and limits the number of farmers who can profitably grow cashews，这个不算论证了方案么？说明了方案的否定性副作用？