There are different users who can be assigned with a workflow task. Based on the given, four out of the five can be provided with a workflow task easily. A workflow will require a certain process that needs to be followed in order to acquire the type of goal that people need to have in the end. This can be assigned to different people and they just have to follow the process in order to get the outcome that they want.
One example of a workflow task is if you would be required to have a document approved. This may need to go through a lot of people for their signatures before you can truly say that the task has been completed.