Consider the following code snippet:

public abstract class Machine

$\{$

public abstract void setRPMs$()$;

$...$

$\}$

You wish to create a concrete subclass named PolisherMachine. $$Which of the following is the correct way to declare this subclass? $$

Question $3$ options:

public class PolisherMachine implements Machine

$\{$

public void setRPMs$()\{...\}$

$\}$

public class PolisherMachine extends Machine

$\{$

void setRPMs$()\{...\}$

$\}$

public class PolisherMachine implements Machine

$\{$

void setRPMs$()\{...\}$

$\}$

public class PolisherMachine extends Machine

$\{$

public void setRPMs$()\{...\}$

$\}$