Which of the following best defines responsive web design?

Responsive web design refers to a design method that dynamically adjusts the layout and content of web pages based on the characteristics of the device that is being used to view them. This involves using flexible grids, flexible images, and CSS media queries to create a seamless viewing experience across a wide range of devices, from desktop computers to tablets and smartphones.

The essence of this approach is its ability to create an adaptable user interface that responds to the size and orientation of the screen, ensuring optimal readability and interaction. This means that when a user accesses a website from a mobile device, the layout reformats itself to suit the smaller screen, maintaining usability and accessibility.

The other options do not encapsulate the full scope of responsive web design. Viewing pages the same on all devices lacks the flexibility and adaptability central to responsive design. Ensuring all elements are visible could indicate fixed designs that do not adjust dynamically. Standardizing functionalities across platforms focuses more on consistency rather than adaptability, which misses the core principle of responsive design.