Getting enough food and supplies for the sodliers.
Take off D; the North had won some battles up to that point. Rip off A; the South would never let go of slavery. Take off B, since the Union had some wins already. You can now clearly see where the answer is.
Answer:
English colonies in North America
D . The heavy Russian losses, combined with food and fuel shortages, led to the abdication of Czar Nicholas II.
B. The Central powers were forced to surrender to the Allied powers as a result of their losses to Russia on the eastern front
