Here the base class member is being protected which is Vehicle. The base class is the Vehicle class and the derived class is Car class.
As the derived class is created or derived from another existing class. So here the class Car has been created through the process of inheritance from the base class which is vehicle. All the methods and variables in Vehicle class are in protected so the only the derived class is able to get access to those variables and methods.
class Car : protected Vehicle
The class Vehicle has been defined earlier and the class Car is created.
The left side is for derived and right side is for base class.
