The approach that is described here is the bottom-up approach.
Explanation:
When a complex job or a project is allotted to a team, it is preferable that the team first opts to form a work breakdown structure of the entire task. This structure enables the team manager to assign specific tasks to the members of the team based on his knowledge of the capability and expertise of each of the members.
The reason this approach is called the bottom-up approach is because the primary and less important tasks are divided amongst the members of the team to be carried out individually and the final and more important tasks are carried out by the team togetherly.