Answer:
Protracted, brutal warfare and mass destruction, village by village
Explanation:
From the 1870s to the early 1900s Africa was subject of aggressive military invasions and pressure from European Powers which lead to the subsequent colonization of almost 90% of the African territory, with only Ethiopia, Liberia and the Dervish state remaining independent. By 1900 the rest of the African territory was colonized by Britain, France, Spain, Belgium, Germany, Portugal and Italy.
The general subject in all of the 7 debates between Lincoln and Douglas was slavery, which was an extremely hot issue then.
I am not positive but I think it’s B