which operating system was the first to include graphical user interface (GUI)?

MAC OS
Linux
Chrome OS
Windows

The operating system that was the first to include a graphical user interface (GUI) is Mac OS.

If you are interested in finding more information about which operating system was the first to include GUI, you can use various methods to research and verify this information:

1. Online Search: Use a search engine like Google or Bing to search for the history of operating systems and GUI. Look for reliable sources such as technology websites, official documentation, or reputable books that document the evolution of operating systems.

2. Books and Publications: Look for books or publications that cover the history of operating systems. They often include details about the introduction of GUI in different operating systems.

3. Official Documentation: Visit the official websites of different operating systems such as Apple, Microsoft, or Linux. They may provide historical information on the development of their respective operating systems, including when GUI was introduced.

Remember to rely on credible and authoritative sources to ensure accurate information.