The correct answer is D: .pptx. The file extension .pptx is the standard extension for presentations created with Microsoft PowerPoint, particularly from PowerPoint 2007 onwards. The 'x' denotes that it is an Open XML format, which replaced the older binary .ppt format, offering improved file recovery and smaller file sizes.
A: .docx is the standard file extension for documents created with Microsoft Word, also from Word 2007 onwards. It is used for text documents, not presentations.
B: .pdf stands for Portable Document Format. It is a universal file format developed by Adobe to present documents, including text formatting and images, in a manner independent of application software, hardware, and operating systems. While PowerPoint presentations can be exported as PDFs,
.pdfis not the native PowerPoint file extension.C: .xlsx is the standard file extension for spreadsheets created with Microsoft Excel, from Excel 2007 onwards. It is used for numerical data, charts, and calculations, not for presentations.