How Profitable Was Slavery

How profitable was slavery?

A) In general, planters would have been better off freeing their slaves and hiring them back.
B) On the best quality cotton land, most planters made a profit; otherwise, most slaveholders lost money.
C) Large-scale planters' return on their investment was roughly equal to what factory owners were making.
D) Slavery was so profitable that thousands of industrialists in the North were selling out each year to invest in cotton plantations.