The correct answer is:
D. The children of female slaves didn't need to be bought.
Plantation owners preferred slaves over indentured servants for various reasons, and one of the significant advantages of using slaves was that the children born to female slaves automatically became the property of the slaveholder. This meant that the slave population could be perpetuated without additional costs of buying new laborers. In contrast, with indentured servants, once their term of service was completed (typically several years), they would be set free, and any children they had during their servitude would not be bound to the owner.
It's important to note that slavery was a deeply exploitative and inhumane system, and the preference for slaves was rooted in the desire for economic gain and power at the expense of the enslaved individuals' freedom and well-being. Slavery has had profound and lasting negative effects on the lives and cultures of the African Americans who were subjected to it, as well as on the broader history of the United States.