This describes a transition plan (also called a release plan) because it focuses on moving a deliverable into production/go-live, defining the target audiences/users, and identifying operational training needs. The CompTIA Project+ objectives explicitly list "Develop a transition plan/release plan" and include example components such as operational training, go live, operational handoff, and identifying internal vs. external audience-all of which match the scenario.
A contingency plan is for responding to risks/issues if something goes wrong, not the standard production handover approach. A scope statement defines what work/deliverables are included and excluded, but it doesn' t detail production cutover, operational ownership, or training. A communication plan defines how information is shared (who, what, when, and through what channels), but it is not specifically the go-live and operational handoff blueprint.
So, because the team is planning deployment/move to production plus user identification and training, they are developing the transition plan.