Imperialism had fed into European tensions because of the high number of European countries competing for colonies all over the world.
D would be the most appropriate. C and B would be very bias, especially since C was written by a general in World War II, meaning that it would only be his point of view and not the other argument. D, is by a trustworthy newspaper columnist (since it's popular) who has read both books and written a view on both which would most likely not be very bias.
Answer: The reason America became involved in WWI was because Germany started sinking American merchant ships around the British isles
Explanation: Originally, America wanted nothing to to with the war because they weren't concerned about about events and alliances in Europe, and thus stayed out of the war. But eventually German forced our hand and we joined.
Using the documents and following rules
It took 6000 hours......................