What is the role of media queries in responsive design?

Media queries play a crucial role in responsive design by allowing developers to apply different CSS styles based on specific characteristics of the device being used to view the content. This includes factors such as the screen width, height, resolution, orientation, and even specific features of the device. By utilizing media queries, designers can create fluid layouts that adapt seamlessly to various screen sizes and resolutions, improving the user experience across devices, from smartphones to large desktop monitors.

The ability to tailor styles to the capabilities of each device enables the implementation of mobile-first designs, where the base styles are designed for smaller screens and enhancements are added for larger screens as needed. This adaptability is fundamental to responsive design, ensuring that content is visually appealing and accessible, regardless of the user's device.

In contrast, the other options do not encapsulate the full purpose of media queries. Adjusting font size responsively is a specific application that might use media queries but does not capture their overall role. Creating fixed layouts directly contradicts the concept of responsiveness, as fixed layouts do not adjust to different screens. Finally, ensuring all images are the same size does not utilize media queries effectively, as responsive design aims for fluidity and adaptability, rather than uniformity in size.