Question 8 (a) What is polymorphism in object oriented programming? Is it really needed and if so, why? What are its advantages? How is it implemented in C++? If it makes your explanation easier, you can use an example. Be precise and brief, in your answers. [5 marks] (b) Should we use the virtual keyword for every method in C+ +? What is a pure virtual function? What is an abstract class in C++? Briefly explain your answer. [3 marks] (c) What is object slicing, and why could using pure virtual functions avoid this problem? [4 marks]