Which of the following is not true of a hierarchy in an Excel Data Model?

a. A hierarchy must be created in the Power Pivot window.

b. Only one hierarchy per table is allowed. For example, it wouldn't be possible to create the hierarchy Continent, Country, Region, City and the hierarchy Continent, Country, State/Province, City, Zip based on a Geography table.

c. A hierarchy is often aided by DAX's RELATED function, so that fields from related tables can be brought into a single table and used in building the hierarchy.

d. A hierarchy's main use is to allow users to drill down through the hierarchy in a pivot table.