imperialism is one nation or group (usually, but not always forcefully) controlling another, so it's not A. colonialism is one nation or group forcefully controlling another and exploiting it economically, so it's not B. utopian socialism is convincing capitalists to peacefully give power to the socialists, so it's not C.
according to the process of elimination, the answer is D. hope this helped!
Very overcrowded Rio de Janeiro. Also to encourage development in the interior.