The correct choice is Mark the comment as the answer to the discussion.

In GitHub Discussions that use the Q and A format you can select a specific reply as the accepted answer. This action highlights the solution with a check mark and surfaces it prominently near the top of the thread which helps readers quickly find the resolution. It also marks the thread as answered which improves discoverability for others with the same issue.

Pin the discussion to the repository keeps the entire thread at the top of the Discussions list but it does not identify a particular reply as the solution and it does not move any comment to the top of the thread.

Convert the discussion to an issue and link back changes the item type and removes Q and A features that support accepted answers. It adds unnecessary overhead and still does not highlight the solving reply inside the original discussion.

Lock the conversation prevents new replies and does not help readers locate the solution. It can also hinder follow up if clarification is needed.

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