What technological achievement occurred in 1947?

The correct answer is the introduction of supersonic air travel, which is significant because it marks a pivotal moment in aviation history. In 1947, the Bell X-1, piloted by Chuck Yeager, became the first aircraft to exceed the speed of sound in level flight, achieving a speed of Mach 1. This event not only demonstrated that supersonic travel was possible but also laid the groundwork for the development of commercial supersonic airliners, which would later revolutionize air travel by significantly reducing flight times.

While the other options present notable technological advancements, they occurred at different times. The first manned moon landing took place in 1969, which was a monumental achievement in space exploration. The discovery of nuclear fission was achieved in the late 1930s and 1940s, leading to significant advancements in both energy production and military technology. Lastly, the development of the Internet emerged much later, primarily in the late 20th century, with the groundwork established in the 1960s through ARPANET. Each of these events is important in its own right, but they are distinct from the advances made in 1947 regarding supersonic flight.