Which of the following best describes a "Responsive Website"?

A "Responsive Website" is best described as a site that adapts to various screen sizes. This means that the website design adjusts fluidly based on the screen dimensions of the device being used—whether it’s a desktop, tablet, or mobile phone. The main goal of responsive web design is to ensure an optimal viewing experience for users by eliminating the need for resizing, panning, and scrolling across a wide range of devices.

Responsive design typically involves the use of flexible grids and layouts, as well as CSS media queries, which allow styles to change dynamically based on the device’s screen width. This approach not only enhances user experience but also improves SEO and increases accessibility, as search engines favor mobile-friendly websites.

In contrast to the other choices, a site that functions only on desktop devices would not be considered responsive, as it doesn't cater to various screen sizes. The requirement for login does not define a responsive design; it pertains to user access rather than layout adaptability. A primarily text-based site could be responsive, but its content type does not inherently enhance its adaptability to different screens. Therefore, the focus on adaptability to various screen sizes makes the second option the best description of a responsive website.