What is the main reason the united states entered the war, according to wilson?

What happened as agriculture became entrenched in the south ?

Prior to the presence of europeans on the continent, the slave trade in africa a) did not exist in any form. b) was limited to internal trade only. c) included the trans-saharan and indian ocean slave trade. d) was rarely needed due to the lack of an agricultural economy.

What role did the alliance system play in preventing austria-hungary and serbia from coming to a compromise settlement?