请教一道题目是否判定正确

The computer company’s present troubles are a result of technological stagnation, marketing missteps, and managerial blunders so that several attempts to revise corporate strategies have failed to correct it.

A.      so that several attempts to revise corporate strategies have failed to correct it.
B.      so that several attempts at revising corporate strategies have failed to correct
C.      in that several attempts at revising corporate strategies have failed to correct them
D.      that several attempts to revise corporate strategies have failed to correct 
E.      that several attempts at revising corporate strategies have failed to correct them

我的判断是这样的：

首先，so that肯定错，没有这种用法；
其次，只剩下前面是that的选项，correct后面无论是跟it还是them都有指代不清的嫌疑；
再次，由于that在从句中充当correct的宾语，所以correct后面不用跟任何代词。

所以，我认为D是答案。

不知道是否正确？请各位大虾指点。