Final answer:
Flak batteries relied on RADAR technology to detect British bombers, helping the RAF to protect cities and respond to Luftwaffe attacks during World War II.
Step-by-step explanation:
Flak batteries, which were anti-aircraft gun installations, relied on the early-warning technology of RADAR (Radio Detection and Ranging) to locate and target British bombers during World War II. These radar systems, having been developed in the 1930s and perfected by the early 1940s, provided a significant advantage to the British. They allowed for the effective coordination of RAF (Royal Air Force) defensive strategies, contributed to intercepting German aircraft en route, and played a key role in protecting population centers from the Luftwaffe during the Battle of Britain and subsequent Blitz.