8. Your lobster fishing business is straightforward, and you run your accounting in Excel. You maintain separate workbooks for each year, and each workbook has a spreadsheet for every month. The monthly spreadsheets are identical except for their names, which are January, February, etc. You have found that you need to sum your diesel fuel expenditures, which are always recorded in cell D18, for the months of August through December. What three-dimensional formula would give you that result? SUMNEW(D18,AUGUST:DECEMBER) SUM(8:12!D18) SUM(March:July!"D18") SUM(AUGUST:DECEMBER!D18)