D. all answer choices are correct
I hope this helps brainliest please
Answer:
The Mexican army attacked them. The main cause of the war was the westward expansion of the United States. All through the 19th century Americans believed it was their right to expand westward. At the time they believed they could conquer the people already living on the land and take it for the United States.
Explanation:
The Red Scare or communism was the <span> political system that emerged directly from world war 1.</span>
