Final answer:
The best description of Nelson Mandela's definition of freedom is that true freedom involves a collective responsibility to enhance the freedom of others, as stated in option B.
Step-by-step explanation:
The quotation that best describes Nelson Mandela's definition of freedom is option B) "For to be free is not merely to cast off one's chains, but to live in a way that respects and enhances the freedom of others." This statement encapsulates Mandela's vision that true freedom involves a communal aspect where personal liberties are tied to the liberty of others, suggesting a shared responsibility in fostering a society where everyone's freedoms are upheld. It aligns with the understanding that freedom is not just an absence of oppression, but also the presence of conditions where all individuals can thrive, and where their choices and actions contribute to the well-being of the community.