Question

what does lincoln threaten to do the the rebelling states if they dont return to the union?
blockade all their ports
free their slaves
sign an alliance with great britain
burn all their cotton plantations and farms
rewatch

Explanation:

Lincoln issued the Emancipation Proclamation, which threatened to free enslaved people in rebelling states if they did not return to the Union by January 1, 1863. Blockading ports was an early military action but not framed as a conditional threat for return; the other options are historically inaccurate to this specific conditional threat.

Answer:

Free their slaves