Explanation:

DOC is a document file format used by Microsoft Word, also used with most word processing software, including OpenOffice. DOC stands for DOCument file. A DOC file can contain formatted text, images, tables, graphs, charts, page formatting, and print settings.

TXT is a file extension for a text file, used by a variety of text editors. ... There is no standard definition of a text file, though there are several common formats, including ASCII (a cross-platform format), and ANSI (used on DOS and Windows platforms).

XLS is a file extension for a spreadsheet file format created by Microsoft for use with Microsoft Excel. XLS stands for eXceL Spreadsheet. Microsoft Excel files use a proprietary format for storing Microsoft Excel documents. This file format is known as the Binary Interchange File Format (BIFF).

RTF is a text file format used by Microsoft products, such as Word and Office. RTF, or Rich Text Format, files were developed by Microsoft in 1987 for use in their products and for cross-platform document interchange. RTF is readable by most word processors.
Hence, option 2 is the correct answer.