Step 1: Quote Interpretation.
The statement "An unexamined life is not worth living" originates from Socrates, a prominent ancient Greek philosopher. Socrates contended that continuous self-reflection and scrutiny of one's principles and conduct are essential for a purposeful existence.
Step 2: Option Evaluation.
- 1. Plato: While Plato documented Socrates' philosophical discussions, the quote is specifically attributed to Socrates.- 2. Buddha: The Buddha's teachings centered on achieving enlightenment and ending suffering, not this particular assertion.- 3. Socrates: Correct. Socrates famously asserted that a life without introspection and inquiry lacks value.- 4. Tagore: Rabindranath Tagore, a poet and philosopher, is not credited with this statement.
Step 3: Final Determination. The accurate identification is 3. Socrates.
Final Answer: \[ \boxed{\text{The correct answer is 3. Socrates.}} \]