Refer to the Exhibit. You are working on creating an OLAP query that outputs several rows of with summary rows of subtotals and grand totals in addition to regular rows that may contain NULL as…

Refer to the Exhibit. You are working on creating an OLAP query that outputs several rows of with summary rows of subtotals and grand totals in addition to regular rows that may contain NULL as shown in the exhibit. Which function can you use in your query to distinguish the row from a regular row to a subtotal row?