Final answer:
The Treaty of Ninety Six is best described as an agreement where Backcountry Loyalists remained neutral during the Revolutionary War, reflecting the complexity of loyalties in the colonies.
Step-by-step explanation:
The best description of the Treaty of Ninety Six is that Backcountry Loyalists agreed that they would stay neutral in the fight against the British during the American Revolution. This understanding reflects the divided allegiances in South Carolina during the revolution, with significant Loyalist sentiment in coastal regions undermining the unified Patriot effort against British control. It's part of the broader context where British strategy focused on the southern colonies, and the revolutionary dynamics included negotiations and allegiances with various populations, including Native American tribes, enslaved individuals, and Loyalists.