Final answer:
The legacy parallel printer port is the Parallel port, which was commonly used to connect printers to computers before USB and Ethernet became prevalent.
Step-by-step explanation:
The legacy parallel printer port among the options given is Parallel. This port, also known as a printer port or Centronics port, was commonly used to connect printers to computers before the advent of USB ports. The parallel port transmits multiple bits of data simultaneously, as opposed to serial ports, which send data one bit at a time. USB (Universal Serial Bus) and Ethernet are more modern interfaces for connecting a variety of devices, including printers, to a computer. Serial refers to serial communication ports, which were also used in legacy systems but are distinct from parallel ports.