Final answer:
The most critical factor in New England's industrialization was the abundance of rivers, which provided the necessary water power for early factories and helped improve transportation and trade networks.
Step-by-step explanation:
The factor that most contributed to industrialization in New England was D. an abundance of rivers. The presence of many rivers in New England provided a fundamental resource for generating water power, which was crucial for operating the machinery in factories during the early stages of the Industrial Revolution.
These rivers also facilitated the construction of canals, which greatly improved trade and transportation networks. While access to raw materials, a well-educated population, and trade relations were also important, it was the abundant water resources that allowed New England to develop its industry rapidly by placing factories alongside these natural water sources.