In engines with system, the lubricating oil can be added to the engine through the filling

In engines with system, the lubricating oil can be added to the engine through the filling hole in the crankcase cover, by using a hand oil can, or through the separator pipe

A.lubricating oil

B.dry sump

C.circulated tank

D.wet sump

请帮忙给出正确答案和分析，谢谢！