Advanced Scrum Case Studies Vol 2: Dealing with demanding stakeholders

You are a Scrum Master and you have a challenge:

You are coaching a new Product Owner doing release planning for the first time. There are three politically powerful stakeholders who each wan their project included as your team's highest priority. It is clear that due to the lack of resources it will be a miracle if even one of the enhancements can be delivered.

The Product Owner asks you what should he do? Which project should he pick and how can he avoid trouble from the two stakeholders w...