一道逻辑题提问！求大神指点！??

DoorbellDong

被这道题折磨了好久。A study followed a group of teenagers who had never smoked and tracked whether they took up smoking and how their mental health changed. After one year, the incidence of depression among those who had taken up smoking was four times as high as it was among those who had not. Since nicotine in cigarettes changes brain chemistry, perhaps thereby affecting mood, it is likely that smoking contributes to depression in teenagers.

Which of the following, if true, most strengthens the argument?


(A) Participants who were depressed at the start of the study were no more likely to be smokers after one year than those who were not depressed.

(B) The study did not distinguish between participants who smoked only occasionally and those who were heavy smokers.

(C) Few, if any, of the participants in the study were friends or relatives of other participants.

(D) Some participants entered and emerged from a period of depression within the year of the study.

(E) The researchers did not track use of alcohol by the teenagers.



正确答案是A，我选了C（看了大家的提问感觉是最不可能的答案哈哈哈）
现在完全能理解A为什么对，但是不知道C为什么错！！


原因是昨天看了Helr的逻辑资料，里面提到相关因果推理题，其中有一道题我觉得和上面这道非常像：
In the year following an eight-cent increase in the federal tax on a pack of cigarettes, sales of cigarettes fell ten percent. In contrast, in the year prior to the tax increase, sales had fallen one percent. The volume of cigarette sales is therefore strongly related to the after-tax price of a pack of cigarettes.

Which of the following, if true, would most strengthen the argument above?

A. During the second year after the tax increase, cigarette sales increased by a significant amount.
B. The information available to consumers on the health risks of smoking remained largely unchanged in the period before and after the tax increase.
C. Most consumers were unaware that the tax on cigarettes was going to increase.
D. During the year following the cigarette tax increase, many consumers had less income, in inflation-adjusted dollars, than they had had in the previous year.
E. During the year after the tax increase, there was a greater variety of cigarettes on the market than there had been during the previous year.


而这道题答案是B，Helr的解释是B选项强调了不存在独立第三因素（对于健康的认知导致的sales下降），因此加强了argument。那按照这个逻辑的话，为什么上面那道题的C选项不对呢？上面那题的C选项说的也是独立第三因素（基因或行为习惯导致depression增加），为什么就不对了呢？


想了半天了，求大神解答！！！???

Pistachio_lin

關於 抽菸跟抑鬱的那一題.

題目連結

題目提供的線索
1. 對象:  青少年 + 從沒抽過菸
2. 研究: 他們是否開始抽菸以及他們是否精神健康有轉變

研究解果:
1. 抽菸的人比不抽菸的人多了四倍出現抑鬱的症狀

‘’結論’’:
1. 抽菸導致青少年抑鬱

先想著 在什麼樣的情況，在題目提供的線索下都為真的情況下，這個結論會不對？

- Reverse causality: 抑鬱的人本身就會去抽菸。
如果是這樣，抑鬱本身的人就會去抽菸，就不是因為抽菸導致抑鬱，是他們本身就抑鬱了。 繞著這個主題打，可以增強或是削弱結論。

- 或是有其他因素造成抽菸跟抑鬱同時發生，我們不知道。
所以能告訴我們，其他有可能的因素是不影響 抽菸<->抑鬱這個連結的，都能加強這個邏輯。

記住: 我們加強與削弱的部分從線索到結論的過程。

答案A: 在研究一開始就抑鬱的人, 相比於那些不抑鬱的人, 在一年後不太有可能成為抽菸的人。

明確按這著個reverse causality的觀念去打。 所以選Ａ.

希望有幫助到你

第二題的部分用上面的邏輯也能推出來，你試試看唄？