Excel Spreadsheet File Extension

The file extension that denotes an Excel Spreadsheet is .xlsx.

Explanation:

Excel is a popular spreadsheet program developed by Microsoft. It is widely used for tasks such as data analysis, budgeting, financial modeling, and more. When you save a spreadsheet in Excel, it is typically saved with a file extension that indicates the file type. The most common file extension for Excel spreadsheets is .xlsx, which stands for "Excel Open XML Spreadsheet".

Other File Extensions:

Let's take a look at the other file extensions mentioned in the options and understand what they represent:

a) .xlr: This is not a valid file extension for Excel spreadsheets. It is more commonly associated with the file format used by some versions of Corel Quattro Pro, a spreadsheet program.

b) .docx: This file extension is associated with Microsoft Word documents, not Excel spreadsheets. It represents the newer file format used by Word, based on XML (eXtensible Markup Language).

c) .xlx: This is also not a valid file extension for Excel spreadsheets. It does not correspond to any known Excel file format.

d) .xls: This file extension was used by older versions of Excel to save spreadsheets. However, the newer versions of Excel, starting from Excel 2007, use the .xlsx file extension by default.

Conclusion:

The correct file extension that denotes an Excel Spreadsheet is .xlsx. While there are other file extensions associated with Microsoft Office products, such as .docx for Word documents, .xlsx is specifically used for Excel spreadsheets.