这一题好像牵涉了很多知识点：

In the mid-1920’s the Hawthorne Works of the Western Electric Company was the scene of an intensive series of experiments that would investigate changes in working conditions as to their effects on workers’ performance.

(A) that would investigate changes in working conditions as to their effects on workers’ performance: would investigate的使用不当，应该使用一般过去时；their指代对象不清楚；as to修饰对象不明确；同时as to在这里的用法不是惯用法。Investigate changes…as to effects没有表示investigate effects that…的意思

(B) investigating the effects that changes in working conditions would have on workers’ performance：正确。这里的would是可以的，would have on…。

(C) for investigating what are the effects in workers’ performance that changes in working conditions would cause：what are多余；介词in (performance)错；in workers’ performance做定语，改变了语子意思，on workers’ performance应该做状语。cause不如have好。

(D) that investigated changes in working conditions’ effects on workers’ performance :句子意思混乱：on workers’ performance可能修饰effects,也可能修饰changes； 句子甚至可以看成（changes in working conditions）的effect on performance。正确的逻辑意思：现象是Changes would have some effects on workers’ performance(changes have effects on performance),调查的对象是effects。（B）

(E) to investigate what the effects changes in working conditions would have on workers’ performance：不定式做定语不恰当（不定式做定语而不是同位语修饰名词的时候，应带有may,can,must,will,should等助动词的意思,而investigate这个动作没有这些情态。就是调查，不是可能调查，会调查，应该调查等等）；what多余；changes前缺少that，不符合标准书面语规范。

但是我不知道C中的for investigating可不可以。不仅不定式，介词+动名词是可以表示目的的，但不知道这里行不行，和分词做定语有什么区别。

请NN指教。