同学你好，该知识点来自沪江网校《新托福中级语法【随到随学班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好，先看下句子的含义：
The climatic changes in southwestern Asia were more subtle, ( )they involved shifts in mountain snow lines, rainfall patterns, and vegetation cover.
subtle: 微妙的，不易察觉的
前半句：亚洲西南部的气候变化比较微妙
后半句：涉及到山区雪线、降雨模式和植被覆盖的变化
两句之间有的是因果关系。
课件16页也提到啦~in that = 因为（For the reason that）
适合这里的因果表达。

其他选项基本都是含义不对，补充一下：in which很多时候是用作where的替代词组，比如：
Near where I live there's a wood where you can find woodpeckers.
Near where I live there's a wood in which you can find woodpeckers.

希望有帮到你。