The correct answer is AFRICA.
African territories were distributed among the different European powers in the Berlin conference and the colonisation process took place during the 19th century. The colonization process in America have almost come to an end, as most former colonies had already gained independence or were about to do it. European powers and the US also had control over Asian territories, but in the 19th century the influences were not as massive as in the African continent. There was almost no free land there.