Hone (verb) means to sharpen or refine something (literally, like sharpening a blade, or figuratively, like improving a skill).
Hone in on is often mistakenly used instead of "home in on", which means to focus closely on something.
I: Correct usage: "Hone" means to refine or improve skills.
II: Correct usage: "Honing" means sharpening the sword.
III: Incorrect usage: The correct phrase is "homed in on" instead of "honed in on."
Thus, sentences I and II are correct, making option (a) the correct answer.
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