Final answer:
The prime phase of a project where work is performed is the Executing phase, where project plans are carried out to meet the objectives.
Step-by-step explanation:
The prime phase of a project where all the planned work is performed is the Executing phase. During the executing phase, the project team carries out the project plans and works to achieve the project objectives. This phase is characterized by the allocation of resources, execution of project plans, and monitoring to ensure that project goals are being met efficiently. It follows the planning phase, where all project activities and schedules are mapped out, and precedes the closing phase, which involves finalizing all activities across all project process groups to formally close the project.