Two technicians are explaining what exhaust gas emissions tell you about engine operation. Technician A says that the higher the level of CO2 in the exhaust stream, the more efficiently the engine is operating. Technician B says that CO2 levels of 20 to 25 percent are considered acceptable. Who is correct?
A. Both Technicians A and B
B. Neither Technicians A and B
C. Technician A
D. Technician B