The central issue was reconstructing the nation after the Civil War.
The correct answer is: "railroads".
Railroads flourished during the 19th century and enabled to travel long in-land distances much quicker than before. They were also one of the main factors that triggered the industrial revolution, as quick transportation reduced production costs and brought important efficiency gains for industries, for instance, in coal mining, and contributed to the development of mass production systems.
John James Audubon is the correct answer
Answer:
the object that rotates is defined as an axis
