Final answer:
In the Penobscot Nation, archaeologists think that a) the availability of fertile soil was a primary factor for some people to settle down and farm on the Central American land bridge, which enabled the growth of crops and the development of a surplus food supply.
Step-by-step explanation:
The settlement of people in the Penobscot Nation on the Central American land bridge for farming is attributed to the availability of fertile soil. This resource would have allowed for the growth of crops necessary to support a settled lifestyle.
As the archaeological record shows, the adoption of agriculture, like the cultivation of the Mesoamerican triad of corn, beans, and squash, provided a surplus of food and enabled the development of complex societal structures.
This is typified by the Mississippian tradition, with a major reason for the cultural shift being the adoption of maize agriculture. Additionally, the abundance of fresh water and the need for stability in the face of environmental challenges and resource scarcity also encouraged sedentary lifestyles and agricultural development.