In an auxiliary diesel engine "by-pass type" lubricating oil system, the main lube oil pump forces __________.

Correct Answer: Option B — some of the oil used by the engine through a filter

In a bypass lube oil system, a portion of the total oil pumped is continuously diverted through a fine filter or purifier, while the majority flows directly to engine bearings. This maintains adequate flow volume and pressure while gradually cleaning the total oil inventory.