Answer : 2. "Ctrl + O"
Explanation :

1. The shortcut key to open File Explorer or File Manager is Ctrl + O.

2. In Microsoft Excel and all other spreadsheet programs, pressing Ctrl+O brings up the Open window, allowing you to load an existing spreadsheet stored on your computer.

3. In Microsoft Word and other word processors, pressing Ctrl+O brings up the Open window, allowing you to load an existing document stored on your computer.