I'm pretty sure it's the national road
One of the Fourteen Points that's- at least- partially inspired the Lusitania was: <span>Freedom of the Seas
In the freedom of the seas, Joseph Kenworthy wrote that Lusitania was sent at a low speed to an area where a boat was waiting to torpedo her ship, causing Lusitania to sink and disappear within the depth of the ocean.</span>
The answer is C. forced to pay reparations to the allies.
The correct answer is either manifest destiny or the civil war
Because of the civil war and the expenses of maintaining a navy that could blockade Confederate ports, the Navy was constantly losing power and ships and after the war ended most of the 700 initial ships were completely out of service. As manifest destiny and reconstruction began spreading, the government did not focus on rebuilding its navy and a large part of the navy that remained had to focus on things like helping merchants or doing civilian runs in order to be sustained.