Which of the following methods can provide alternative text for an informative background image?

In the context of web accessibility, alternative text is crucial for ensuring that all users, especially those using assistive technologies like screen readers, can understand and interact with web content. The use of the aria-label attribute on a span element is effective in providing an accessible name or description for an element that may not otherwise have one.

When applied correctly, the aria-label attribute can convey significant context or information about an image that serves as a background, especially if that image is meant to convey important information. This descriptive text can summarize what the background image represents, allowing those who cannot see it to comprehend its relevance to the content of the page.

Other methods, such as setting visibility to hidden or display to none, do not provide any beneficial context for users relying on assistive technology. These options effectively remove the element from the accessibility tree, making it invisible to screen readers. Additionally, using an image tag generally involves directly including a graphical image which may not be applicable for background images typically specified through CSS. Therefore, using aria-label on a span is the most appropriate choice for providing alternative text for informative background images.