哪位NN能给我解释下无关和他因的区别吗？

我做题时有时觉得这个选项是他因削弱之类的。比如

Lightbox, Inc., owns almost all of the movie theaters in Washington
                        County and has announced plans to double the number of movie screens it has in the county within five years.  Yet attendance at Lightbox’s theaters is only just large enough for profitability now and the county’s population is not expected to increase over the next ten years.  Clearly, therefore, if there is indeed no increase in population, Lightbox’s new screens are unlikely to prove profitable.
            

Which of the following, if true about Washington
                    County, most seriously weakens the argument?

中的B选项

The sales of snacks and drinks in its movie theaters account for more of Lightbox’s profits than ticket sales do.

答案解释说的的是无关所以不选。那么无关和他因到底区别在什么地方呢

i have the same question!!! push

先说句矫情的话：有关无关的判断是在长期做题，对题目的感觉上建立起来的。多看看OG11，对于无关选项的解释。我之前也疑惑过，总把正确选项当无关排除掉。后来做多了就好了。

回到这题:首先，这题不是因果关系题，所以先不考虑他因的问题。其次，这里虽然谈得是profitable,但是注意，结论说的是new screen，因此，答案应该围绕这个来谈。而饮料啥的赚不赚钱就无关。我知道你会说如果饮料占了大部分那么票卖不出去也可以创收。可是来的人都买吃的么？人数不增加的话吃的赚得钱可以弥补影院运营的钱么？这些信息文中都没有，所以吃的东西就是无关的。无论是weaken还是support题都要紧密围绕文中信息或称推理链来展开。

这题没给正确选项，我预测一下（错了不要骂我）：可以从人口这入手，比如说人口可能有变化，会有更多人进电影院。或者说新增加的电影院地理位置在以前没有电影院的地区。

谢谢上面几位的解答~~~~

PS:那个正确的答案是

 Though little change in the size of the population is expected, a pronounced shift toward a younger, more affluent, and more entertainment-oriented population is expected to occur.