Answer:
B. Monarchy
Step-by-step explanation:
United States were a part of the British Empire until second half of the 18th Century. Revolutionary war that started in 1775 finished in 1783, when the Treaty of Paris was signed and United States were recognized as independent state.
In 1917 Revolution that started in Russia led to the fall down of the Romanov dynasty that ruled in Russia for 300 years. After the war, Russian Empire disappeared and Soviet Union was created.