Which of the listed diesel engine systems is likely to create the problem of a cylinder regularly misfiring?（）

A.overloading the engine
B.low exhaust valve lift
C.excessive cylinder cooling
D.insufficient mechanical clearance

A.exhaust manifold
B.valve bridge
C.pressure of the fresh air charge
D.valve adjusting gear

A.excessive compression pressure
B.air in the fuel lines
C.high fuel pressure
D.excessive load