TTML stands for which of the following?

The correct answer, Timed Text Markup Language, is indeed a standard designed for the representation of timed text streams, which include captions and subtitles. This markup language is essential for ensuring that content is accessible to people with hearing impairments, as it provides time-based text that synchronizes with audio-visual media.

Timed Text Markup Language supports various features like timing, formatting, and placement of text on the screen, which enhances the viewer's experience and understanding of the content. This standard is particularly important in educational contexts and media production, where accessibility is a priority.

The other choices do not accurately reflect the purpose or functionality of the language. Text Type Markup Language and Table Text Markup Language do not exist in the context of timed or synchronized text, while Time Text Markup Language is a misinterpretation of the actual term, further emphasizing the importance of having the correct terminology when discussing accessible content.