Answer:
Urbanization
Explanation: Millions poured into cities for jobs in factories during the industrial era. This rapid urbanization resulted in overpopulation, crowded tenements, strain on city service, health issues etc.
Shay's Rebellion highlighted major problems with the Articles of Confederation because State governments had difficulties fixing their economies and raising militias for defense. Shay's Rebellion highlighted the need for a stronger central government to prove for the economic welfare and civil defense of the newly formed United States.
The correct answer is B.
The USS Maine battle ship was quietly riding anchor in Havana harbor, Cuba. At 9.40 pm on the night of February 15th, 1898, the ship was blown up apparently by a mine, in an explosion which tore out its bottom and sank, killing 260 officers and men on board.
No one ever established exactly what caused the explosion but it nevertheless resulted in the brief American - Spanish war because America strongly suspected the Spanish were the culprits.
I think that a central idea to democracy is that people should discuss their differences and settle any conflicts by compromise rather than by one side imposing their will or through opened (armed) conflict
