Hi I think I may be able to help you out. I think even though Theodore Roosevelt was known as the "trust buster" and C sounds quite logical that A would be the way to go. The companies didn't necessarily want to "bully" smaller companies. The big businesses were trying to make lots of money fas and make sure small companies didn't catch up so they had all the power. I'd choose A however C does include the trusts he broke up. I think they phrase it that way to throw you off and make you fall for C. I believe it is A because it is what Roosevelt's main goal was but just didn't include how. If I were you I'd choose A as well.
