O 71. Two technicians are inspecting an exhaust sys. tem. When he taps on the muffler with a mallet. Tech- nician A hears noise coming from inside the muffler and says that it is most likely rotting out from the in- side. Technician B says that this type of failure is due to chemical damage. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B A. Technician A only B. Technician B only C. Both A and B O D. Neither A nor B Question 72 72. A technician has just flushed a cooling system. Which of the following statements should he adhere to when refilling the system? A. Make sure the fresh antifreeze is the same color as that which was drained. E. Use a 50/50 mixture of water and antifreeze. C. Bleed air from the system only if the vehicle has a bleeder valve. D. none of the above A, Make sure the fresh antifreeze is the same color as that which was drained. O B. Use a 50/50 mixture of water and antifreeze. O C. Bleed air from the system only if the vehicle has a bleeder valve. D. none of the above. Question 73