You are a DevOps engineer working on a custom action.

For JavaScript custom actions, the metadata file supports lifecycle scripts through the runs section. The correct key for a script that runs before the main action entrypoint is pre, and the correct conditional key for controlling whether that pre-script runs is pre-if. Therefore, option B is the only valid metadata structure. GitHub Actions does not use start, start-if, before, or before-if as action metadata keys. Option C is also invalid because pre-if only defines a condition; it cannot contain both a condition and a script reference in one line. In GitHub Actions exam terms, this tests custom action metadata, JavaScript action lifecycle hooks, and conditional execution before the main action logic.

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