A; Along the coast of the Gulf of Mexico (The Tuxtlas Mountains)
The market forces regulate production to align with the supply. As demand increases, the supply is increased to meet the new demands. when the government controls production there may be a surplus of goods that are not needed and a scarcity of basic goods. The economic principles that inform production may be undermined by political agendas.
A is the answer. The first Bull Run was early in the war, and much of the North was convinced it would end quickly-people had even brought out chairs to watch the firefight. However, their visions were soon shattered.
B is wrong: the South had plenty of troops, and even if it did not, Bull Run was no indication.
C is wrong: Bull Run was a failure for the North, so it would not indicate to Lincoln that the North was overstocked on troops.
Similarly, D is wrong: the war actually would take longer.