Final answer:
The Pentagon was constructed by the U.S. Army Corps of Engineers. Alfred Thayer Mahan did not believe the reopening of the American frontier was necessary for empire building. The Sedition Act was not a measure for securing men and materials for war, unlike other wartime administrations and acts.
Step-by-step explanation:
Organizations Responsible for Building the Pentagon and American War Effort Regulations
The organization responsible for the construction of the Pentagon was the U.S. Army Corps of Engineers. They handled the project, which aimed to consolidate military offices and provide a highly functional headquarters for the U.S. Department of Defense during World War II.
The Pentagon remains one of the most iconic military buildings in the world.
Regarding the question about Alfred Thayer Mahan's beliefs on building an American empire, he did not see the reopening of the American frontier as necessary.
Mahan was an advocate for a strong navy, establishing military bases around the world, and a canal through Central America to assert and protect U.S. interests abroad.
For the measures enacted to secure resources for World War I, the only options not directly related to procuring men and materials were legislative means like the Sedition Act.
The Food Administration, the Selective Service Act, and the War Industries Board were all crucial instruments in organizing the country's resources and labor for the war effort.