Which of the following is true regarding the profitability of slavery?

Question 3 options:

Charles Sydnor accurately estimated that the profitability of a slave was only about 2.4%well below the 5-6% return that could have been earned on bonds at the time.

Rates of return on slaves were, on average, higher in the North compared to the South.

Salve prices varied with age. For instance, slaves 30 years-of age or older would sell for higher prices than a 20 year-old slave.

Robert Evans found that the average rental data for slaves imply rates of return varying from 9.5% to 18.5% depending on the region and time period.

All the above are true.