Answer:I believe the answer is tanks.
Explanation:Tanks are armored vehicles designed to combine the military factors of fire, maneuver and protection. Although the concept of armored vehicles preceded the Great War, the tank was specifically developed to overcome the stalemate of trench warfare on the Western Front that followed the First Battle of Ypres (19 October-22 November 1914). The marrying of recent technological advances, such as the internal combustion engine with armor plating, enabled the tank’s development during World War I.
I think the answer is true
During the 19th century, the United States ability to remain isolated from European affairs was largely due to its "geographic location," since it is bordered by the two largest oceans in the world.
If the machine or person cannot do the job then they are replaced.