For the Class AB output stage shown in Fig. P5, we know that Q3 and Q4 are the major power BJTs which deliver current to load resistance RL. Please give your answer and brief explanation for the following questions: (a) In addition to provide two VBE voltage drop for biasing the Q3 and Q4 like the conventional diode-connected biasing circuit does, what is the major advantage of the input stage which consists of Q1 Q2, R and R? (b) What is the major purpose of the last stage which consists of Q5 Q6, R3 and R4? (c) What is the major purpose of the resistors R5 and R6? Vi R -Vcc +Vcc [Q R +Vcc R R33 R53 R6 R43 -Vcc Fig. P2 R