The correct answer is D.
Step-by-step explanation
The American Civil War was a conflict that pitted the forces of the Confederate States of America against the forces of the Union nationalists between the years 1861 to 1865. This war was motivated mainly by the issue of slavery since the southern states (Condeferados) defended the rights of the states to expand slavery, while the northern states (Union) defended the civil rights of slaves to become free citizens.
This war was characterized by the technological difference between the north and the south because in the north there was more industry, which contributed to the manufacture of arms, ammunition, and food for the army. Meanwhile, the southern states suffered from war shortages and were heavily dependent on arms smuggling to keep their troops capable of fighting. However, this did not impede to make it difficult for the Union to win as they used a defensive strategy that allowed them to balance forces with the Union armies.
So the correct answer is D.