问题如下：
If the cost of producing coffee relative to sugar is lower in Coffeeland than in Sugarland. With trade, the sugar industry in Coffeeland would most likely:
选项：
A. contract.
B. Uncertain.
C. expand.
解释：
A is correct.
Because the cost of producing coffee relative to sugar is lower in Coffeeland than in Sugarland,Coffeerland will export coffee and the coffee industry will expand.At the same time,Coffeeland will import sugar so the sugar industry will contract.
考点：比较优势
解析： 在Coffeeland， 生产Coffee 的机会成本比 sugar低，那么该国生产Coffee就具有比较优势，所以该国就应该生产Coffee。从而该国生产sugar的行业就应该收缩。
这里的cost就是指opportunity cost嘛？