The one that was a factor in the U.S entry in world war I was :
B. the sinking of the Lusitania
Some mining camps started to grow into towns or cities as more people started pooling into the mining camps the population started expanding and also precious metals like gold was often found.
Explanation:
The population explosion required more building as camps could no longer accommodate such huge numbers.
Mining also led to employment, a boom in business and prospects of a healthy income on a regular basis. The finding of gold further led to wealthy business prospects.
As the camps started changing into towns and cities with more settlements facilities like railroads, schools and hospitals along with markets were also built.
When the delegates to the Virginia convention debated the Constitution in June 1788, they did so under the assumption that an aye vote there would provide the vital, deciding ninth affirmative needed for ratification.
