To significantly improve content usability for diverse audiences, which technique is vital?

Providing alt-text on images is a vital technique to significantly enhance content usability for diverse audiences. Alt-text serves as a descriptive text that conveys the content and function of images, making them accessible to users who rely on screen readers or have visual impairments. This inclusivity helps to ensure that all users can comprehend and engage with the visual aspects of the content, enhancing their overall experience.

In contrast, varying font sizes may help improve readability for some users but does not address the needs of those who rely on assistive technologies. Using complex language could alienate or confuse readers, reducing usability overall. Adding background music may distract users or create accessibility issues for those who prefer content without audio cues. Therefore, providing alt-text is the most effective method for improving content usability across varied audiences.