The correct answer to this open question is the following.
We think that the correct question should be this one: What is a reason the New England and the middle colonies had fewer slaves than the southern colonies?
If that is the case, then the correct answer is the following.
The New England colonies were located in a territory that had no fertile soil. Indeed, it was a rocky land, no good for growing abundant crops, as was the case of the southern colonies and middle colonies. That is why New England colonies had few slaves and colonists made a living by hunting, fishing, and trading.
In the Southern and Middle colonies, the land was more fertile and owners had large plantations where crops such as cotton, rice, or tobacco were grown. The larger plantations needed many slaves to produce the kinds of crops that were consumed in the colonies and exported to Europe.