2. Create a pivot table that shows sales revenue by region (column) for each of the four years and quarters. Correct any errors in the original dataset in the worksheet that are revealed in this initial pivot table. Once you have corrected the errors in the original data set, create a new pivot table to reflect the corrected data. Insert a pivot chart that shows the sales revenue trend by region over the four-year period. In the pivot chart, the x-axis should be years and the y-axis should be sales revenue. What trends do you see in the pivot table and pivot chart? 3. Create a pivot table that shows sales revenue, variable cost, and contribution margin for each year for each region. 4. Create a pivot table to answer the question "What was the most profitable brand in each year, as measured by contribution margin?" Don't show the Grand Totals.