Important information that is communicated using both color and text is an example of which web accessibility principle?

The correct choice here is based on the principle of perceivability in web accessibility. Information that is communicated using both color and text ensures that it is accessible to diverse users, including those who may have visual impairments or color blindness. By using multiple ways to convey information, such as combining visual elements (color) with written language (text), content accommodates varied perception and enhances clarity.

This principle is central to accessibility because it mandates that users can perceivably access and understand content regardless of their individual capabilities or the technologies they are employing. Thus, providing information through both means not only adheres to best practices in web design but also aligns with standards for inclusivity.

The other principles—understandable, operable, and robust—focus on different aspects of accessibility. For instance, understandability pertains to how easily the information can be comprehended, operability relates to the functionality of the interface for all users, and robustness involves the adaptability of web content to various platforms and user agents. While these principles are also crucial in creating an accessible experience, they do not directly address the method of presenting information through dual modalities like color and text.