Hello Paigejosie1071
Answer: The best answer out of your choices would be A
Reason: Choice A seems to be the most correct answer, assisting the newly freed slaves wasn't a problem after the war.
Choice B was a problem after the war because they had to recruit new soldiers to replace the dead and wounded.
Choice C was also a problem the infrastructure was a mess and need rebuilding.
Choice D was a big problem as well the economy was in shreds mainly because Confederate money was useless.
Hope That helps you!
-Chris