Final answer:
European nobility was not a viable labor source option for the early Europeans colonizing North America, as they focused on indentured servants, Native Americans, and African slaves due to the need for a controllable and permanent workforce.
Step-by-step explanation:
The group that was not a viable choice to use, by Europeans, as an ongoing labor supply in the early colonizing of North America was d. European nobility. This is because the European colonists turned to different sources for the labor they required. At first, they relied on indentured servants and attempted to enslave Native Americans, but both groups proved to be insufficient due to high death rates, escape, and resistance. In the case of European nobility, attempting to coerce labor would not have been feasible due to their high social standing and the European social and legal structures that protected them.
Ultimately, colonists favored Africans as laborers because they did not succumb to diseases from which Europeans suffered at the same rates and were unfamiliar with the New World's terrain, making it harder for them to escape. Additionally, due to the fact that Africans could be enslaved for life and their children were born into slavery, this guaranteed a more permanent and controlled labor source for the European colonists.