[单选题]Why did President Lincoln issue the Emancipation Proclamation? A Because President Lincoln himself was an abolitionist. B Because he wanted to punish the slave-owners in those states which broke away from the union. C Because he has no other alternative. D Because he realized that in order to win the war, he should make it a just war against slavery so as to rally as many people as possible under the banner of the Federal Government. E F