The Task Options selection criteria for this report allows you to specify:
Show Tasks - If this option is selected, the report output will include details for each task.
List all tasks / Rollup Tasks Dropdown - The default value "List all tasks individually" will show all details summarized to the appropriate level based on the other selected reporting options. The remaining options in this dropdown will result in the output being summarized to a particular level of the task work breakdown structure (WBS). Details for the specified level of the WBS and those lower in the WBS hierarchy will be "rolled up" and included in each amount. This is a way to summarize various legs of a WBS to an intermediate level.