Final answer:
The middle colonies became known as the 'breadbasket' colonies due to their fertile land and long growing season, which allowed farmers to produce a surplus of grain such as wheat. The well-developed merchant class in the middle colonies coordinated the export trade and introduced technological innovations to stimulate shipbuilding and associated industries.
Step-by-step explanation:
The geographical advantage that most helped the middle colonies become known as the 'breadbasket' colonies was their fertile land and long growing season. Farmers in the middle colonies were able to grow a variety of grains such as wheat, rye, oats, barley, buckwheat, and corn, as well as vegetables, flax, hemp, and raise livestock. This abundance of agricultural resources allowed the middle colonies to produce a surplus of grain, particularly wheat, which could be sold to both internal and external markets.
Furthermore, the middle colonies had a well-developed merchant class that coordinated the export trade and introduced technological innovations to lower shipping times. This stimulated shipbuilding and associated industries, contributing to the economic growth and prosperity of the middle colonies.