Answer:
Using the context clue, the best definition of pivotal as it is used here is critically important. So, the right option is B.
Explanation:
John Buchanan’s “The Road to Valley Forge,” narrates the complete story of how Washington grew from an inexperienced Backwoods General to a true Commander-in-Chief of a fighting force. America's greatest hero is revealed through the book.
He was intelligent and courageous who struggled desperately to learn from his mistakes, who converted a diverse mix of militiamen into a real army, and who exhibited to all the Americans that they could become create their own destiny. So, 1775 was a pivotal year for the Americans because that year was a turnaround point in their lives.