What is a characteristic of a serial interface in data transmission?

A characteristic of a serial interface in data transmission is that bits are sent one at a time over a single wire. This method of transmission allows for simpler wiring and reduced complexity compared to parallel transmission, where multiple bits are sent simultaneously over multiple wires. Serial interfaces are commonly used in various applications, including telecommunications and computer connections, because they can efficiently transmit data over longer distances with less interference and data degradation.

The sequential nature of serial data transmission makes it optimal for many scenarios where speed and distance are essential, balancing simplicity with performance. This is why the choice aligning with the principle of sending one bit at a time over a single channel is the correct answer.