[求助]逻辑一道求助

Galanin is a protein in the brain. In an experiment, rats that consistently chose to eat a fatty foods when offered a choice between lean and fatty foods were found to have significantly higher concentrations of galanin in their brains than did rats that consistently chose lean over fatty foods. These facts strongly support the conclusion that galanin causes rats to crave fatty foods.

Which one of the following, if true, most supports the argument?

(A) The craving for fatty foods does not invariably results in a rat's choosing those foods over lean foods.
(D) The rats that preferred fatty foods had the higher concentrations of galanin in their brains before they were offered fatty foods.

为了省事，只贴出存疑的两个选项。正确答案是D。

我觉得A比D更靠谱点。不过A也显得比较含糊，因为它的用词“ does not invariably ”意思是“不总是”，我可以理解为“在大多数时刻”或者是“在少数时刻”。若是前一种理解，那么可以有效的削弱原argument。因为此时可以认为“the craving for fatty foods ”可能是造成“rats with significantly higher concentrations of galanin consistently chose to eat a fatty foods ”的原因。若是后一种理解，那么可以有效的加强原argument。因为此时可以认为“the craving for fatty foods ”可能不是是造成“rats with significantly higher concentrations of galanin consistently chose to eat a fatty foods ”的原因。

但是D就是很迷惑。“The rats that preferred fatty foods ”在没有吃fatty foods之前的galanin含量更高。我可以认为是吃fatty foods引起了galanin含量的降低，这样就是削弱，因为因果倒置。也可以认为是galanin含量降低引起了吃fatty food，这样就是加强，因为重申因果。

总之，就是没想明白。希望nn们指点一下，谢谢~

这应该属于一类题型：两个事件同时出现，把一个看成是另一个的原因

如：在这道题中，产生galanin 和chose fatty food 两个事件是试验中同时被观察到的，结论却说 产生galanin 是 chose fatty food的原因

这种题型，如果是weaken：一，他因，证明因果是错误的

                        二、证明因果被倒置了，也就是说结论中的原因其实是结果，而结论中的结果其实是原因

support自然就和weaken相反，就如同这道题，正是排除了 因果倒置的可能，说明肯定不是chose fatty food 导致 产生galanin