Final answer:
Benjamin Franklin's remark, 'a republic... if you can keep it,' signifies the necessity for the citizens to actively uphold and maintain the principles of republicanism and democratic representation established by the newly framed government.
Step-by-step explanation:
The statement that best describes what Benjamin Franklin meant when he said, "a republic...if you can keep it." is b) Franklin believed that the people needed to actively maintain and preserve the republic. This reflects the understanding that a republic would require constant effort and vigilance by its citizens to sustain its form of government based on the consent of the governed and to avoid it from devolving into a tyranny or monarchy. The Constitutional Convention established a government that was a product of the consensus that authority rests with the people and not a monarchy. James Madison and his contemporaries believed in a republican form of government that derived its power from the people and was administered by representatives elected for a limited time or during good behavior. This new system was a balancing act, requiring active participation from its citizens to elect representatives and uphold the principles of the revolution and republicanism.