Yeasts capable of leavening bread are widespread, and in the many centuries during which the ancient Egyptians made only unleavened bread, such yeasts must frequently have been mixed into bread doughs accidentally.  The Egyptians, however, did not discover leavened bread until about 3000 B.C.  That discovery roughly coincided with the introduction of a wheat variety that was preferable to previous varieties because its edible kernel could be removed from the husk without first toasting the grain.

Which of the following, if true, provides the strongest evidence that the two developments were causally related?

1. Even after the ancient Egyptians discovered leavened bread and the techniques for reliably producing it were well known, unleavened bread continued to be widely consumed.
2. Only when the Egyptians stopped the practice of toasting grain were their stone-lined grain-toasting pits available for baking bread.
3. Heating a wheat kernel destroys its gluten, a protein that must be present in order for yeast to leaven bread dough.
4. The new variety of wheat, which had a more delicate flavor because it was not toasted, was reserved for the consumption of high officials when it first began to be grown.
5. Because the husk of the new variety of wheat was more easily removed, flour made from it required less effort to produce.

不知道这道题是否已经被讨论过了。感觉无一选项正确。烦请指路，多谢多谢。

选C啊, 他的问题是让我们证明wheat variety 和leaven bread dough是因果关系,

他前面说了那么多就是说是那个麦子的壳无意识的引入发酵了面包而不是 直接加入yeasts 发酵面包, C刚好就说明这一点, 因为麦子的壳是可以吃的，而且不用加热就可以剥去，Ｃ说加热了就破坏了a protein that must be present in order for yeast to leaven bread dough.

诚心感谢二位楼上的指引，明白了许多。只惭愧我的思路仍然不是很清晰。于是我把题干译成中文，借以理清逻辑主线如下：

英文原文：

Yeasts capable of leavening bread are widespread, and in the many centuries during which the ancient Egyptians made only unleavened bread, such yeasts must frequently have been mixed into bread doughs accidentally.  The Egyptians, however, did not discover leavened bread until about 3000 B.C.  That discovery roughly coincided with the introduction of a wheat variety that was preferable to previous varieties because its edible kernel could be removed from the husk without first toasting the grain.

Evidence: Heating a wheat kernel destroys its gluten, a protein that must be present in order for yeast to leaven bread dough.

中文译文：

能使面包发酵的酵母广泛流传，在古埃及人仅烘制无酵面包的几百年中，这种酵母一定不时地被不经意地掺入面团中。但是，直到公元前3000年的时候古埃及人才发现了发酵面包。该发现与一种小麦的流入的时间大致相同，这种小麦较之前的品种更受欢迎，因为它的可食用的麦粒可以不经整粒烘烤而去壳。

证据：加热小麦的麦粒破坏其麸质，麸质是一种让酵母发酵面团所必须的蛋白质。

逻辑主线：

1、               公元前3000年前，古埃及人烘烤面包时使用酵母，但他们不知道酵母的作用。

2、               这时所用于制作面包的小麦是必须经过加热才可以去皮的。

3、               麦粒的麸质是一种让酵母发酵面团所必须的蛋白质。

4、               由于加热破坏麦粒的麸质，酵母并未发生其应有的作用。

5、               公元前3000年，古埃及人引入了新的小麦品种。

6、               该品种可以不经烘烤而去壳，因此麦粒的麸质不被破坏。

7、               这种小麦较之前的品种广受欢迎。

8、               古埃及人在用这种小麦制作用于烘面包的面团时依旧不经意地掺入酵母。

9、               古埃及人发现面团发酵了…

分析：

如果去掉下划线的部分（即答案C所给信息），问题是：对原小麦和新小麦同样使用酵母，为什么酵母使新小麦发酵了？ 则答案显然是C。

我想这道题的难点在于第8点是关键点，但题干并未给出，需要从第1点推出，于是我头脑中不能及时反应出题目在考对新老小麦在其他条件相同情况下的比较。换句话说，如果出题人把答案C的内容揉入题干，仍旧可以出一道较为简单的Inference的题（答案是第8点）。所以，一道题即考了Support又考了Inference。