Proper lubrication of the main bearing is more easily obtained in a single acting four-stroke/cycle diesel engine than in a single acting two-stroke/cycle diesel engine because （）

A.bearing pressure in a four-stroke/cycle acting single diesel engine is continually reversed

B.bearing pressure in a two-stroke/cycle single acting diesel engine is continually reversed

C.the maximum bearing pressure is higher in a single acting two-stroke/cycle diesel engine

D.two-stoke/cycle diesel engines require more complicated lubrication piping