What is a proper guideline for sharpening tools?

A. Most hand tools must be sharpened using a power grinder.
B. You should never clean a file with a wire brush between uses.
C. Make all strokes with a file in a backward motion, holding the file at different angles for each stroke.
D. When sharpening axes, Pulaskis, and brush hooks, the filing direction should always be away from the eye toward the cutting edge.