Last reviewed
Correct answer: B. It sees only the diff and the criteria, and is not the one that just wrote the code
Explanation
The principle — what makes a review independent is who reviews and what they can see.
Why the key is correct — Anthropic is precise: a reviewer in a fresh subagent context sees only the diff and the criteria you give it, not the reasoning that produced the change, so it evaluates the result on its own terms. The benefit: a fresh context improves code review since Claude will not be biased toward code it just wrote.
Why the others are wrong — the absent reasoning is the point, not a flaw. Extra room is a reason to delegate, not why reviews improve. The author checking again is what a fresh reviewer replaces: the bias belongs to whoever wrote the code, so re-reading keeps it.
Remember this — a reviewer that did not write the code judges it rather than defends it.
Sources — Anthropic's Claude Code best practices.
Sources
“A reviewer running in a fresh subagent context sees only the diff and the criteria you give it, not the reasoning that produced the change, so it evaluates the result on its own terms.”
“A fresh context improves code review since Claude won't be biased toward code it just wrote.”
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