You've been asked to aggregate the following data so that you have sales by department by day. Of the three columns, "Date," "Sales," and "Dept," which one$($s$)$ identify the grouping and which one$($s$)$ should be aggregated?

Columns that identify the grouping: "Date." Columns to aggregate: "Sales" and "Dept."

Columns that identify the grouping: "Dept." Columns to aggregate: "Sales" and "Date."

Columns that identify the grouping: "Sales." Columns to aggregate: "Date" and "Dept."

Columns that identify the grouping: "Date" and "Dept." Columns to aggregate: "Sales."