The correct answer is option 'C' - Windows 95.

Explanation:
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Windows 95 was a major milestone in the history of Microsoft Windows operating systems. It introduced several significant features, one of which was the first-ever implementation of the Start button and Start menu.

1. Introduction of the Start button:
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Windows 95 was released on August 24, 1995, and it replaced the previous Program Manager interface with a new user interface. One of the key elements of this new interface was the addition of the Start button, which was located in the bottom-left corner of the screen. The Start button was a graphical representation of the Windows logo and was designed to provide quick access to various features and functions of the operating system.

2. Functionality of the Start menu:
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When the Start button was clicked, it opened up the Start menu. The Start menu was a hierarchical menu that allowed users to access programs, settings, and files on their computer. It provided a centralized location for launching applications, accessing system utilities, and navigating the file system.

The Start menu consisted of several key components:
- Programs: This section displayed a list of installed programs, allowing users to launch applications by selecting them from the menu.
- Documents: Here, users could find recently accessed documents, making it convenient to open frequently used files.
- Settings: This section provided access to various system settings, such as control panel options, printers, and network configurations.
- Search: The Start menu also included a search feature that allowed users to search for files, folders, and applications on their computer.
- Help and Shutdown: These options provided assistance and allowed users to shut down or restart their computer.

The introduction of the Start button and Start menu in Windows 95 revolutionized the way users interacted with the operating system. It provided a more user-friendly and efficient way to access applications and system functions, making it easier for users to navigate and utilize the features of Windows.

Windows 95 introduced the first-ever Start button and Start menu.