Here is my take on it. As I read through the problem, there is a parallel construction and comparison here, which I didn't see any mistake in. and looked for tense after that, again no mistake. so A. just to confirm, again going through rest of answer choices.

(A) altered the investment strategies of United States corporations more radically than those of
(B) altered the investment strategies of United States corporations more radically than
wrong comparison, investment strategies of US are compared with foreign corporations, it should be strategies of foreign corporations
(C) altered the investment strategies of United States corporations more radically than they have
wrong comparison, investment strategies of US are compared with foreign corporations, it should be than they have altered investment strategies of foreign corporations
(D) radically altered the investment strategies of United States corporations more than
wrong comparison, investment strategies of US are compared with foreign corporations, it should be strategies of foreign corporations
(E) radically altered the investment strategies of United States and
It is changing the meaning, comparison is missing here. strategies of united states have been altered more than that of Foreign corporations


Hence A.