which of the following is supported by the excerpt?

"you dislike the emancipation proclamation; and, perhaps, would have it retracted. you say it is unconstitutional—i think differently. i think the constitution invests its commander-in-chief, with the law of war, in time of war. the most that can be said, if so much, is, that slaves are property. is there—has there ever been—any question that by the law of war, property, both of enemies and friends, may be taken when needed? "—president abraham lincoln, 1863 letter

a. the president maintained correspondence with confederate leaders he respected
b. defining slaves as property started to create support for the president in the south.
c. people in the north thought the president planned to force former slaves to fight.
d. resistance to the president's policies existed within the union itself during the war.