Event Driven Computing Question 9 (a) What is a callback function in event driven computing? [2 marks] (b) In event driven programming, list three possible classes of events to be han- dled in typical graphical user interfaces. [2 marks] (c) An event driven program (such as used by graphical user interfaces) has the following typical structure in the main loop: int main(.. .) setup); main-loop(); return 0; // set callback functions why do you need this? What is the goal of the function main.loop in the event driven program above