Questions: A printer is behaving erratically; you suspect a faulty parallel port. Which tool can you use to test the parallel port? Multimeter Ammeter Cable tester Loopback plug

The answer is the fourth one (or D): Loopback plug.

Explanation for each option:

1. Multimeter: A multimeter is used to measure electrical properties such as voltage, current, and resistance. While it can be useful for checking the electrical characteristics of a port, it is not specifically designed to test the functionality of a parallel port.

2. Ammeter: An ammeter is used to measure current. Similar to the multimeter, it is not designed to test the functionality of a parallel port.

3. Cable tester: A cable tester is used to check the integrity and connectivity of cables. It is not suitable for testing the functionality of a parallel port itself.

4. Loopback plug: A loopback plug is a diagnostic tool used to test the functionality of ports by sending signals back to the device. It is specifically designed to test the functionality of parallel ports and other types of ports.

Summary: To test a faulty parallel port, the appropriate tool to use is a loopback plug.