In Scrum, if the Development Team realizes they have selected too much work after starting the Sprint, they should engage with the Product Owner to adjust the scope. This might involve removing some work from the Sprint Backlog, which can help ensure the remaining work can be completed within the Sprint. It is better to adapt the Sprint scope early on rather than wait until the Sprint Review, where it may be too late to take corrective action. Adjusting the definition of 'Done' or adding more team members are not suitable practices within the Scrum framework.