The correct answer is A) bearing pressure in a four-stroke cycle single acting diesel engine is continually reversed. In a four-stroke cycle single acting diesel engine, the main bearings experience continuous pressure reversals as the engine goes through its intake, compression, power, and exhaust strokes. This continuous reversal of bearing pressure helps to maintain a lubricating oil film on the bearings, ensuring proper lubrication. In contrast, in a two-stroke cycle single acting diesel engine, the bearing pressure is not continually reversed, as the engine only has a power and exhaust stroke. This can make it more challenging to maintain a consistent lubricating oil film, resulting in the need for more complicated lubrication piping and systems. The other options are incorrect because they do not accurately describe the key differences in lubrication between four-stroke and two-stroke cycle diesel engines.