Which term is described by the phrase 'Automatic repeat query'?

• A. Automatic repeat query
• B. Check digit
• C. Echo check
• D. Parity check

Answer: (A)

The main idea being tested is how reliable data transmission is achieved by automatically asking for a retransmission when something goes wrong. The phrase describes a mechanism where the sender transmits a block of data and then automatically requests a repeat (retransmission) if an error is detected or if an acknowledgment isn’t received in time. This is the behavior of Automatic Repeat Query, often shortened to ARQ, a standard approach to ensure data arrives correctly over noisy channels.

So the term that matches this idea is the one that literally conveys automatic repeated requests for data. The other options describe different error-detection methods: a check digit is a calculated value added to data to catch mistakes in a single item, a parity check adds a parity bit to help detect errors but doesn’t handle retransmission, and an echo check involves sending back received data to verify it was received correctly but isn’t the automatic retransmission protocol by itself.