What is the difference between `Runnable` and `Thread` in Java?

• A. `Runnable` is a class, while `Thread` is an interface
• B. `Runnable` defines a task; `Thread` represents execution
• C. `Thread` is used for defining tasks, while `Runnable` is an execution thread
• D. Both are the same, used interchangeably

Answer: (B)

The distinction between Runnable and Thread in Java lies in their fundamental purposes and design. Runnable is an interface that defines a task that can be executed by a thread. It contains a single method, run(), which encapsulates the code that constitutes the task to be executed.

On the other hand, Thread is a class that represents the execution of a thread of control in a program. When you create an instance of the Thread class, you can pass a Runnable implementation to its constructor, thus associating a specific task with that thread. The Thread class directly manages the execution of that task.

This structure allows for cleaner separation between defining a task and managing thread execution. You can create multiple threads that execute the same Runnable task, allowing for greater flexibility and reuse of code. This separation is crucial in multi-threaded programming, making it easier to manage complex tasks and ensuring that the task logic is decoupled from the thread management logic.

The other options do not accurately describe the relationship and functionality of these two elements in Java. Hence, the key insight is the distinction between defining the task with Runnable and executing that task through the Thread class.