Which war revealed to the united states that it was unprepared for modern war mobilization?
a. the mexican american war
b. the civil war
c. the spanish american war
d. world war i

World War I

Explanation: This has to be the answer because during the first World War, the United States saw how unprepared they were compared to other countries such as Japan and Germany. Although Japan and Germany had a lot of resources in the beginning of the war, their supplies and resources were vanishing because they kept attacking and never surrendered, unlike Japan who fought to the last man standing.

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c, because the american revolution was from 1765 to 1783.