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Correct answer: B. Editing your source files, while it researches and proposes changes
Explanation
The principle — separate deciding what to do from doing it, and review the decision first.
Why the key is correct — Anthropic defines plan mode as a permission mode where Claude researches and proposes changes without editing your source files. Research is encouraged; the write is what is withheld until you have seen the plan.
Why the others are wrong — it is not the ordinary mode run slowly, because something specific is withheld. Reading is not restricted, since exploring is the whole purpose. And it is not defined by when questions are asked.
Remember this — reach for plan mode when you want the approach reviewed before anything lands on disk.
Sources — Anthropic's Claude Code glossary.
Sources
“A permission mode where Claude researches and proposes changes without editing your source files.”
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