Well... you see that choice b is a correct answer. Choice c is really a more specific case of b. Choice b could more properly read that "None, some or all of the numbers 0 through 9 could be printed."
The JVM exits when all
user threads exit. Daemon threads are non-user threads, and the JVM may exit with them running. In your example choice c could occur if the main
thread completes before any of the daemon threads produce output.