The class correctly implements the Runnable interface with a legal public void run() method.

Option A is incorrect because interfaces are not extended; they are implemented.

Option B is incorrect because even though the class would compile and it has a valid public 

void run() method, it does not implement the Runnable interface, so the compiler would complain 

when creating a Thread with an instance of it.

Option D is incorrect because the run() method must be public.