Which of the following is an output capability of HDMI cables?

HDMI cables are primarily designed for the purpose of transmitting high-quality audio and video signals from a source device, like a computer, gaming console, or media player, to a display device, such as a monitor or television. This ability to carry both audio and video over a single cable is one of HDMI's most significant advantages, simplifying connections and helping reduce cable clutter.

The capability of providing audio and video output through HDMI is critical in modern audio/video setups. It allows users to enjoy high-definition content without the need for multiple cables and connections for separate audio and video channels. In contrast, while data transfer is a function of HDMI, it is not its primary use case, which deals specifically with streaming audio and visual content. Additionally, HDMI cables do not serve to input power to devices or engage in megabit transfer as a primary function, making the focus on audio and video output the most relevant and accurate description of HDMI cables' capabilities.