Which USB version has a maximum transfer rate of 12 Mbps?

The version of USB that has a maximum transfer rate of 12 Mbps is USB 1.1. While USB 1.0 introduced the USB standard and had a maximum speed of 1.5 Mbps in its low-speed mode and 12 Mbps in full-speed mode, USB 1.1 was an update that fixed several issues and provided a more reliable implementation of the original specification. Thus, USB 1.1 solidified this 12 Mbps speed as its upper limit for full-speed connections.

USB 2.0 significantly increased the maximum transfer rate to 480 Mbps, and USB 3.1 GEN 1 further improved this, offering up to 5 Gbps. These advancements reflect the ongoing evolution of the USB standard, enhancing performance for a variety of devices and applications. Therefore, USB 1.1 stands out as the correct answer when discussing the specific maximum transfer rate of 12 Mbps.