Answer:a. to establish ability to build forts
Explanation:
<span>Background of US conflict with Soviet. During World War II, Roosevelt followed a policy of "the Grand Alliance" with the determination to get along with the Soviet Union. He was determined to follow this policy after the war and believed the United Nations, one of his pet projects, would maintain the postwar peace.</span>
<span>They were able to turn flat figures into three dimensional figures using perspective it portrayed death and distance and felt more realistic.</span>
