Final answer:
The 1938 radio adaptation of 'The War of the Worlds' by the Mercury Theater caused panic among listeners, as many believed the dramatized Martian invasion to be an actual news event.
Step-by-step explanation:
The broadcast that sent listeners into panic on the night before Halloween in 1938 was a radio adaptation of H.G. Wells’ The War of the Worlds, presented by the Mercury Theater on the Air. The dramatization was so realistic that many listeners believed an actual alien invasion was taking place, especially since it was formatted as a series of radio news reports. The idea that Martians were invading New Jersey caused widespread alarm despite later clarifications that it was merely a Halloween eve performance.