单选题 By the mid-1960s, cotton farmers in Central America found that pesticides
A．were wiping out 50% of the pests plaguing the crops.
B．were destroying 50% of the crops they were meant to protect.
C．were causing a 50% increase in the number of new pests reported.
D．were costing 50% of the total amount they spent on their crops.

【正确答案】 D

【答案解析】[解析] 这道题目的定位除了通过mid-1960s以外，还可以通用过全部答案都有的一个数字50%来定位，很容易就可以找到原文。这道题目其实就是问这50%是什么，原文中有50%of the financial outlay on cotton production，即财务支出，只有D项涉及了cost。
[干扰项] 本题的关键在于将financial，outlay与costing对应，其他三项没有太大干扰性。