Final answer:
Richard Henry Lee was convinced of the need for American independence from Great Britain due to the influence of Thomas Paine’s pamphlet, Common Sense, which made a compelling case for separation and a republican government.
Step-by-step explanation:
When Richard Henry Lee spoke of being 'convinced of the necessity of separation,' he was referring to the influence of (Option:a)Thomas Paine’s Common Sense. Published in January 1776, Paine’s pamphlet argued in a clear and compelling manner that the American colonies had a right to be independent nations, separate from Great Britain. His use of 'simple facts, plain arguments, and common sense' appealed to the average colonist and this radically shifted the public opinion towards the idea of independence. This work made a powerful case for breaking away from British rule, challenging the monarchy and advocating for a republican form of government.
Paine’s influence was significant as it turned the population towards the revolutionary cause, making the concept of separation and the creation of a new nation based on democratic principles resonate with many. The widespread support and enthusiasm generated by Common Sense played a crucial role in paving the way for Richard Henry Lee and others in the Continental Congress to support and eventually declare independence from Great Britain, culminating in the drafting and approval of the Declaration of Independence.