The most common instrument used to measure diesel engine exhaust pressure is the （）

A.a leaking fuel injector nozzle
B.a clogged air filter
C.excessively early fuel injection
D.malfunctioning valves

A.crankcase
B.piston
C.cylinder liner
D.crank cheek

A.discharge exhaust gases and smoke
B.furnish energy to the turbocharger
C.reduce engine room noise
D.all of the above