What should a product owner do when informed about a blocking issue affecting the sprint?

When a Product Owner is informed about a blocking issue affecting the sprint, reprioritizing the backlog is the most appropriate action. This is because the Product Owner is responsible for maximizing the value of the product and managing the product backlog. Addressing a blocking issue may involve assessing the priority of various backlog items, and it might make sense to shift focus to tasks that can help alleviate the problem or add the most value in the current situation.

By reprioritizing the backlog, the Product Owner can ensure that the team is working on the highest-priority items that can either assist in resolving the blocking issue or deliver the most value to stakeholders. This approach aligns with Agile principles, which emphasize flexibility and responsiveness to change in circumstances.

The other options, such as extending the sprint duration or assigning additional team members, are typically not recommended as they do not follow the Scrum framework's guidelines for managing sprints effectively. Ignoring the issue is counterproductive, as it can lead to further complications and a potentially less successful sprint outcome.