The correct option is All of these configurations because each listed YAML configuration will cause the workflow to run when an issue is opened.

GitHub Actions exposes an issues event that fires when an issue is opened. You can listen to all issue events which will include opened or you can add a types filter set to opened so that only the opened action triggers. Both the single line array form and the multiline list form for the types filter are valid YAML and they behave the same for this event. Therefore the choice that states all of them is correct.

on: issues: types: [opened] would indeed run when an issue is opened, yet it is not the best selection here because more than one configuration satisfies the condition and the correct choice acknowledges that.

on: issues would also run when an issue is opened since it listens to all issue events, but it is not the best selection because multiple configurations meet the requirement and the correct choice reflects that.

on: issues: types: - opened would likewise run when an issue is opened because it is an equivalent YAML form of the types filter, but it is not the best selection since the correct choice confirms that all shown configurations work.

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