The correct answer is Excel - .xl.MS Excel is an electronic spreadsheet developed by Microsoft.It is a program that is used to save and analyze numerical data.A spreadsheet is in the form of a table comprising rows and columns.The rectangular box at the intersection point between rows and columns forms a cell.Files created in MS Excel is known as workbook.The extension used in MS Excel is '.xlsx' Additional InformationExtensionFormat.aacWindows audio file.emlEmail file created by Outlook Express, Windows Live Mail, and other programs..exeExecutable program file.jpg, .jpegJoint Photographic Experts Group photo file.pngPortable Network Graphics File.pptxMicrosoft Powerpoint .docxMicrosoft Word 2007 file