how should the work in agile teams be decided?

Choice 1 of 5:The team should be self-organising; they should decide for themselves who does what work.

Choice 2 of 5:The work should be allocated based on who does what role, for example the tester should do the testing work.

Choice 3 of 5:Either a Scrum Master or Project Manager should allocate the work to each team member.

Choice 4 of 5:Each client will specify how they want the team to do the work.

Choice 5 of 5:The more senior people in the team decide what they want to do, and the more junior people are told to do the rest.