Step 1: Understanding the Book 'Laws'.
The book 'Laws' is written by Plato and is one of his later works. It is a dialogue that explores the nature of law and the structure of an ideal state.
Step 2: Analyzing the Options.
- 1. Plato: Correct answer. Plato is the author of 'Laws', where he discusses the philosophical concepts of justice and governance.
- 2. Aristotle: Aristotle's works include 'Nicomachean Ethics', 'Politics', etc., but not 'Laws'.
- 3. Socrates: Socrates is the main character in many of Plato’s works but did not write 'Laws'.
- 4. Protagoras: Protagoras was a pre-Socratic philosopher and did not write 'Laws'.
Step 3: Conclusion.
The correct answer is 1. Plato.
Final Answer:
\[
\boxed{\text{The correct answer is 1. Plato.}}
\]