What philosophical work is associated with Plato?

The philosophical work most closely associated with Plato is "The Republic," which is one of his most famous dialogues. In this text, Plato explores various themes including justice, the ideal state, the philosopher-king, and the role of the individual within society. He presents his vision of a just society and articulates his theories on knowledge, reality, and the nature of the good life.

This choice is correct because "The Republic" is fundamentally a work of political philosophy and is central to Platonic thought. It serves as a foundational text for Western philosophy and political theory, influencing countless thinkers and discussions throughout history. Other works listed, while significant in their own rights, do not pertain to Plato or his philosophical inquiries. "Up From Slavery" relates to the life and thoughts of Booker T. Washington, "Walden" is a reflection on simple living by Henry David Thoreau, and "Nineteen Eighty-Four" is a dystopian novel by George Orwell.