Hello.
I would say that the most suitable answers are: A. the greatest presence of industry in the North and C. the large amounts of foreign aid received by the North.
I chose these two options because according to historians the North was more industrialized and produced the 90% of its firearms and even the North had a richer agriculture than the South. Also, historias agree that the North had more foreign support than the South, even slaves form the South fought in the Union armies. These two options are the most suitable causes of the North's victory during the Civil War.
Hope this helps.