How did the alliance system in Europe most likely contribute to the start of World War I? • The countries in the alliances sought protection against enemies by sharing military personnel
O The countries in the alliances agreed to work together to gain power through colonization
O The countries in the alliances agreed to share economic resources based on open trade markets
The countries in the alliances signed treaties agreeing to defend each other in times of war

it is D The countries in the alliances signed treaties agreeing to defend each other in times of war.

Explanation:

here are some major conflicts i found. maybe pick one and do more research on it. (cause i ain't writing 6 paragraphs)

in 1877, the nez perce war took place.

1881 - president james garfield was assassinated.

1882 - the chinese exclusion act was passed.

1883 - a decision in the civil rights cases legalized racial segregation in the united states.

1887 - the dawes act was passed.

1893 - the panic of 1893 took place. (what a creative name)

and there are probably other topics you can find if you just search up "united states timeline," or "conflicts in the 19th century for america."

then once you find a topic you like find out how it affected the people of america and what not. (sorry if this feels a bit short changed, history was and never will be one of my strong topics)