What tool is used to true the edge of a sharpened knife?

The correct choice is the honing rod, commonly referred to as a honing steel. This tool is specifically designed to realign and true the edge of a knife after it has been sharpened. Unlike sharpening tools that remove material from the blade to create a new edge, the honing rod aligns any microscopic jagged edges that may have bent or misaligned during regular use. By using a honing rod regularly, one can maintain a sharp edge on knives without having to sharpen them frequently, which prolongs the life of the knife and improves cutting performance.

The other tools mentioned serve different purposes. A butcher steel, while often mistaken for a honing rod, typically refers to a longer, heavier version used in commercial settings for the same purpose. A whetstone is used for actual sharpening, removing material to create a new edge, and a sharpening jig assists in holding the knife at a proper angle while sharpening, but does not itself true the edge.