The correct answer is B) Pressure lubrication. In small high-speed diesel engines, pressure lubrication is the standard method used to lubricate the bearings. Pressure lubrication systems use a pump to circulate lubricating oil under pressure to the various bearing surfaces, ensuring adequate and consistent lubrication. This is more reliable and effective than other methods like splash lubrication, which may not consistently reach all the necessary components. The other options are not typically used for this application. Sight feed lubricators are more common in larger engines, while mechanical lubricators are more suitable for slower-speed engines where the lubrication requirements are less demanding.