Which of the following statements provides support for the claim above?

I.    An effort to help feed-grain producers resulted in higher prices for their crops, but the higher prices decreased the profits of livestock producers.

II.   In order to reduce crop surpluses and increase prices, growers of certain crops were paid to leave a portion of their land idle, but the reduction was not achieved because improvements in efficiency resulted in higher production on the land in use.

III.   Many farm workers were put out of work when a program meant to raise the price of grain provided grain growers with an incentive to reduce production by giving them surplus grain from government reserves.

(A) I, but not II and not III

(B) II, but not I and not III

(C) I and III, but not II

(D) II and III, but not I

(E) I, II and III

正确答案是c

问题：1. I 选项中的livestock producers 算不算 group whose livelihood depends on farming?

           2. II 选项中牵涉到的两个group分别是？

thanks

1. 理论上livestock producers也属于农业产业链上的一部分。whose

livelihood depends on farming作为大农业产业链的参与者理解。

2. II选项只有一个group，所以错。

关于这道题的 III 我有一点疑问。
III. Many farm workers were put out of work when a program meant to raise the price of grain provided grain growers with an incentive to reduce production by giving them surplus grain from government reserves.

这句话 when... 后面的部分的主干是: a program provided grain growers with an incentive by giving... 上面句子的蓝色字体部分应该都是 a program 的内容。我不明白的是这个旨在提高农作物价格的 program，如何通过向种植者提供更多的 grain 来达到目的。grain 多了，价格会降低才符合逻辑啊！请高人指点一二。