The answer is C) Only once he was convinced it was necessary to save the union.
Lincoln said "When, early in the war, General Fremont attempted military emancipation, I forbade it, because I did not then think it an indispensable necessity. When, a little later, General Cameron, then Secretary of War, suggested the arming of the blacks, I objected, because I did not yet think it an indispensable necessity. When, still later, General Hunter attempted military emancipation, I forbade it, because I did not yet think the indispensable necessity had come.
