Final answer:
The following that was not a significant advantage held by the American colonists in the Revolutionary War is that a well-trained and disciplined army. The correct option is c.
Step-by-step explanation:
During the Revolutionary War, one significant advantage the American colonists did not have was a well-trained and disciplined army. The Continental Army faced challenges in terms of training, discipline, and military experience compared to the British forces, which were a professional and well-disciplined army.
The other options—familiarity with the terrain, foreign support from France and Spain, and motivation with a strong cause—were key advantages for the American colonists during the conflict.
The correct option is c.