单选题Some medium and high-speed diesel engines require reduction gear units to provide a useful propeller speedIn most reduction gears, the bull gear（）Amust churn the oil in the sumpBis connected to the propeller shaftCis driven at the highest RPMDcompensates for alignment variations between the engine and pinion gear
单选题
Some medium and high-speed diesel engines require reduction gear units to provide a useful propeller speedIn most reduction gears, the bull gear（）
A
must churn the oil in the sump
B
is connected to the propeller shaft
C
is driven at the highest RPM
D
compensates for alignment variations between the engine and pinion gear
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