Answer :
d. It freed all slaves in states rebelling against the union.
The emancipation proclamation that was signed by Abraham Lincoln on 1st January 1863 declared that all the slaves in states that were then engaged in rebelling against the Union were free forever.
However, this did not mean that all slaves were freed, but it was the starting step towards the later increased fight to end slavery. The emancipation proclamation shifted view of Abraham Lincoln about slavery which would see the civil war's main aim change from preserving the union to the fight to end slavery. Later on the efforts to abolish slavery would increase leading the the final freedom of slaves.
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