The correct answer is option 'A': Winword.exe

Explanation:
- Microsoft Word is a popular word processing software developed by Microsoft. It is a part of the Microsoft Office suite of applications.
- When you want to open Microsoft Word on your computer, you need to execute the appropriate file that triggers the program to start. In the case of Microsoft Word, the file that starts the program is called "Winword.exe".
- The ".exe" extension stands for executable, meaning it is a file that can be executed or run by the computer's operating system.
- The "Winword.exe" file is the main executable file for Microsoft Word, and it is responsible for starting the program and loading all the necessary components and resources.
- When you double-click on the Microsoft Word shortcut icon or select the program from the Start menu, the operating system looks for the "Winword.exe" file and executes it to launch Microsoft Word.
- The "Winword.exe" file is usually located in the installation directory of Microsoft Office on your computer. The exact location may vary depending on the version of Office and the installation settings.
- By starting the "Winword.exe" file, you initiate the loading process of Microsoft Word, and soon you will see the Word application window appear on your screen.

In summary, to start Microsoft Word, you need to execute the "Winword.exe" file, which is the main executable file for the program. This file is responsible for launching Microsoft Word and loading all the necessary components and resources.