Final answer:
Considering windmill as a metaphor for the larger fight in the American Civil War, the argument was not resolved through diplomacy or mutual agreement, but through a prolonged war that deeply impacted both sides of the conflict.
Step-by-step explanation:
The 'windmill' argument, if metaphorically used to describe the dispute between the Confederate South and the Union North, isn't resolved in a simple manner. Wars have their unique characteristics; they often last longer than anyone expects. Such was the case during the American Civil War.
The Northerners and Southerners both initially anticipated a swift resolution, but the war extended, deeply affecting life in both regions. Considering the given options, it is not clear which of A), B), C), or D) is correct without specific historical context relating to 'windmills'.
However, the larger conflict ended with the Union's victory, and reconstruction period entered thereafter. If the windmill is seen as a symbol of this larger conflict, then perhaps it could be said that the argument was resolved through war, not diplomacy or mutual agreement.
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