The correct answer is status was Done AND status = 'To Do'.

status was Done AND status = 'To Do' works because status was Done finds issues that at some point had the Done status and status = 'To Do' restricts results to issues that are currently in To Do. Together they return issues that were Done in the past and are now back in To Do which matches the definition of reopened for this project.

status changed from Done to 'To Do' is incorrect because that clause only matches issues that had a single direct transition from Done to To Do. It can miss issues that were Done and then passed through other statuses before returning to To Do.

status was not in ('In Progress', 'Done') is incorrect because it finds issues that were never in In Progress or Done. That is the opposite of what is required and it will not locate issues that were previously Done.

status = 'To Do' AND resolution is EMPTY is incorrect because it returns all unresolved issues currently in To Do. New issues that were never Done will also match this query so it does not specifically find reopened items.

status = Reopened is incorrect because the project uses only To Do, In Progress and Done. There is no Reopened status in this project so that query will not return the reopened issues described in the question.

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