The Bike and EBike classes are implemented as shown by the code below.

public class Bike { private String make; private int numGears; private double tirePressure; public Bike(String m, int g, double t) { make = m; numGears = g; tirePressure = t; } public void pumpTire() { tirePressure += 5.0; } } public class EBike extends Bike { private int batteryLevel; public EBike(String m, int g, double t, int b) { super(m, g, t); batteryLevel = b; } public void chargeBattery() { batteryLevel++; } }

A new private int variable, currentGear is added to the Bike class. Which of the following describes the best implementation of a changeGear method which would allow the value of currentGear to be changed by instances of the Bike and EBike classes?

A public changeGear method is added to the Bike class only.

A public changeGear method is added to the EBike class only.

A private changeGear method is added to the EBike class only.

A private changeGear method is added to the Bike class only.

A private changeGear method is added to both theBike and EBike classes.