Answer:
C. America would have remained isolationist.
Step-by-step explanation:
The Monroe Doctrine was a doctrine that positioned America against colonialism and the world isolation that European countries established colonies throughout the American environment. According to this doctrine, America should prevent the domination of Europeans on the continent, not allowing the creation of more colonies and allowing American countries to be free and have been of any kind of isolation.
If this doctrine had not been formulated, America would remain isolationist, where all of its production and services would be exclusive to the Europeans who dominated it.