An increase in diesel engine crankcase pressure generally indicates excessive（）

A.large dirt particles in the oil supply
B.insufficient lubricating oil and overheating
C.normal wear
D.water contamination of the lube oil

A.excessive lube oil pressure
B.the proper seating of new rings
C.a worn cylinder liner
D.a malfunctioning cylinder relief valve

A.starting the engine while hot
B.knurling the piston skirt
C.operating the engine overheated
D.scuff resistant piston rings