Which of the following is NOT a method to connect external hard drives?

The method that is NOT used to connect external hard drives is HDMI. HDMI, or High-Definition Multimedia Interface, is primarily designed for transmitting high-quality video and audio signals between devices, such as TVs, monitors, and home theater systems. It is not intended for data transfer between storage devices and computers.

In contrast, USB (Universal Serial Bus), eSATA (External Serial Advanced Technology Attachment), and Thunderbolt are all established standards specifically designed for connecting external devices, including hard drives, to a computer. USB is widely used for its versatility and compatibility with many devices. eSATA provides a direct connection to SATA drives, allowing for faster data transfer rates, while Thunderbolt offers high-speed data transfer along with the ability to daisy chain multiple devices.

Therefore, while the other options are valid methods for connecting external hard drives, HDMI does not serve this purpose.