A is a goal, but not a progressive goal, so A is discarded as a correct answer. And we can say the same thing to B.
Although breaking easing the requirements to become a U.S. citizen might be seen nowadays as a progressive goal, it was not the case back in William Howard Taft's time and it certainly was not his goal. So it can't be D either.
So in the end, we have C. breaking up business trust and giant monopolies.
and he did, like his predecessor Teddy Roosevelt.