Consider the following Java program using threads: public class Threads2 implements Runnable { public void run() { System.out.println("run."); throw new RuntimeException("Problem"); } } public class TestThreads2 { public static void main(String[] args) { Thread t = new Thread(new Threads2()); t.start(); System.out.println("End of method."); } } Which of the following outputs best describes what happens when this program runs?

Introduction / Context:
This question examines how Java threads execute and how uncaught exceptions in a separate thread interact with the main method. It helps you understand that starting a thread does not block the main thread and that runtime exceptions thrown inside a thread produce stack traces independently of the main program flow.

Given Data / Assumptions:

• There is a class Threads2 that implements Runnable and overrides the run method.
• The run method prints "run." and then throws a RuntimeException with the message "Problem".
• The main method creates a new Thread with a Threads2 instance, starts it, and then immediately prints "End of method.".
• We are interested in the typical sequence of visible output, including the exception trace.

Concept / Approach:
When t.start() is called, the JVM creates a new thread of execution and calls its run method in that separate thread. The main method continues executing and prints "End of method." without waiting for the thread to finish. In the worker thread, run prints "run." and then throws a RuntimeException. Because the exception is not caught inside run, it becomes an uncaught exception in that thread. The Java runtime prints a stack trace to standard error that begins with java.lang.RuntimeException: Problem. The exact interleaving of prints from the main thread and the worker thread is not strictly guaranteed, but in many exam style scenarios the main thread line appears first, followed by the worker thread output and its exception.

Step-by-Step Solution:
Step 1: The main thread starts executing main, creates a Thread object, and calls t.start().Step 2: The call to start returns quickly, and the main thread proceeds to System.out.println("End of method."); which prints that line to standard output.Step 3: In parallel, the new thread invokes run(), which prints "run." and then throws new RuntimeException("Problem").Step 4: Since the exception is uncaught in the run method, the JVM prints a stack trace beginning with java.lang.RuntimeException: Problem for that thread.Step 5: Putting these together, a typical observed sequence is "End of method." then "run." followed by the exception trace, so option D best describes the combined output.

Verification / Alternative check:
Running this code on a standard JVM usually shows "End of method." printed first, then "run.", and finally the stack trace. However, thread scheduling is nondeterministic, so in practice "run." could appear before "End of method." on some runs. Exam questions normally ignore this subtle timing detail and expect you to recognize that both lines are printed and that the exception trace appears because the runtime exception is uncaught in the worker thread.

Why Other Options Are Wrong:
Option A shows only the exception and ignores both print statements, which is incomplete. Option B shows "run." and the exception but omits "End of method.", even though the main method definitely prints it. Option C shows "End of method." and the exception but omits "run.", which is also printed by the worker thread. Option D is the only option that includes both normal outputs and the exception trace.

Common Pitfalls:
A common mistake is assuming that calling start executes run in the same thread and blocks until it finishes. In reality, start creates a new thread and returns immediately. Another pitfall is ignoring the difference between exceptions in the main thread and exceptions in worker threads; uncaught exceptions in worker threads do not stop the main method once it has completed. When analyzing thread related questions, always think about which code runs in which thread and how their outputs can interleave.

Final Answer:
The program typically prints "End of method." from main, then "run." from the worker thread, and then displays a java.lang.RuntimeException: Problem stack trace, as described in option D.