Explanation: Each Excel file is called a workbook because (3) it can contain many sheets including worksheets and chart sheets. In Microsoft Excel, a workbook is a file that can contain multiple sheets or tabs. These sheets can be of different types, such as worksheets for data entry and analysis or chart sheets for creating charts and graphs. A workbook provides a structure for organizing and managing data within Excel. It allows you to have multiple sheets within a single file, making it easier to organize related data and perform various calculations and analyses. The ability to have multiple sheets in a workbook is one of the key features of Excel and provides a powerful way to organize and manage data effectively. So, the correct answer is (3) it can contain many sheets including worksheets and chart sheets.