B. An oilstone - its rectangular shape will help you easily because the angels will help you sharpen the knife by the way you want it. If you stroke it to a smaller angel the sharper the edge will be.
Also called sharpening stone or whetstone is a stone that is lubricated with oil used for sharpening knives and other cutting tools. Oilstones come in a variety range of shapes, sizes, and material compositions. They could be made from natural materials or man made materials.
